The Riverside Museum was conceived during an era of architectural innovation. Thomas Hartwell designed the distinctive structure in _____ by...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

• The Riverside Museum
  • was conceived
    • during an era of architectural innovation.

• Thomas Hartwell
  • designed the distinctive structure
    • in 1927[?]

• by the following decade,
  • it
    • had become the city's most celebrated example of Art Deco architecture.

Understanding the Meaning

Let's start reading from the beginning:

The first sentence gives us background:

• 'The Riverside Museum was conceived during an era of architectural innovation'
  • This museum was planned during a time when architects were doing innovative things.

Now the passage tells us about the architect:

• 'Thomas Hartwell designed the distinctive structure in 1927'
  • We learn who designed it (Hartwell) and when (1927).

This is where we have the blank.

Let's look at the choices:

• We're deciding what punctuation (if any) should come after 1927.

To see what works here, let's read the rest of the sentence and understand what it's saying!

• 'by the following decade, it had become the city's most celebrated example of Art Deco architecture'
  • By the 1930s (the decade after 1927), this building had become the most famous Art Deco building in the city.

Now let's understand what we have structurally:

Before the blank:

• 'Thomas Hartwell designed the distinctive structure in 1927'
  • Subject: Thomas Hartwell
  • Action: designed
  • What: the distinctive structure
  • When: in 1927
  • This is a complete thought that could stand alone as its own sentence.

After the blank:

• 'by the following decade, it had become the city's most celebrated example of Art Deco architecture'
  • When: by the following decade
  • Subject: it (the structure)
  • Action: had become
  • What it became: the most celebrated example
  • This is also a complete thought that could stand alone as its own sentence.

What do we notice about the structure here?

• We have two complete sentences that are closely related in meaning:
  • First: Hartwell designed it in 1927
  • Second: By the next decade, it became famous

• These are separate complete thoughts, but they're telling one connected story about the building's history.

So we need a semicolon. A semicolon is specifically designed to connect two complete sentences that are closely related - it shows they belong together while respecting that each is grammatically independent.

The correct answer is D (1927;).

GRAMMAR CONCEPT APPLIED

Connecting Two Complete Sentences with a Semicolon

When you have two complete sentences (called independent clauses in grammar terms) that are closely related in meaning, you have several correct options:

Option 1 - Separate as two sentences:

• Thomas Hartwell designed the distinctive structure in 1927. By the following decade, it had become the city's most celebrated example.

Option 2 - Connect with a semicolon:

• Thomas Hartwell designed the distinctive structure in 1927; by the following decade, it had become the city's most celebrated example.
• The semicolon shows these thoughts are connected while respecting that each is a complete sentence

Option 3 - Connect with comma + coordinating conjunction:

• Thomas Hartwell designed the distinctive structure in 1927, and by the following decade, it had become the city's most celebrated example.
• Coordinating conjunctions: and, but, or, nor, for, so, yet

What you CANNOT do:

Join with just a comma (comma splice):

• Thomas Hartwell designed the distinctive structure in 1927, by the following decade...

Run them together with no punctuation (run-on sentence):

• Thomas Hartwell designed the distinctive structure in 1927 by the following decade...

In this question: Both parts before and after the blank are complete sentences that are closely related (both about the museum's history), making the semicolon the perfect choice to connect them.