Question 238·Easy·Boundaries
The completion of the Transcontinental Railroad was _____ It linked the eastern and western United States, transforming commerce and travel.
Which choice completes the text so that it conforms to the conventions of Standard English?
For punctuation/boundary questions, first decide what kind of sentence you’re dealing with: statement, question, or exclamation. Then check what comes before and after the punctuation—identify whether each side is a complete sentence (with its own subject and verb). If both sides are complete sentences, they generally need a period, semicolon, or a comma with a conjunction, not just a comma. Finally, choose the option whose punctuation matches both the sentence type (tone) and the grammatical structure, and be especially wary of question marks or exclamation points that change the sentence type without any real reason in the context.
Hints
Decide what kind of sentence it is
Ask yourself: Is the first part (“The completion of the Transcontinental Railroad was ___”) a question, an exclamation, or just a statement?
Look closely at what comes after the blank
Check whether the words after the blank (“It linked the eastern and western United States…”) form a complete sentence with their own subject and verb.
Match punctuation to sentence type and structure
Think about which punctuation mark correctly ends a normal statement and also separates it from a new complete sentence that begins with “It.”
Watch out for comma splices
Remember that you cannot connect two complete sentences with just a comma; that error is called a comma splice.
Step-by-step Explanation
Identify what kind of sentence it is
Read the first part as if it were complete: “The completion of the Transcontinental Railroad was _____” followed by the next sentence: “It linked the eastern and western United States, transforming commerce and travel.”
Ask: Is the first part asking a question, showing strong emotion, or just making a factual statement? It is clearly a factual statement describing the railroad, not a question or a shout of emotion.
Check if the next words start a new sentence
Look at the words after the blank: “It linked the eastern and western United States, transforming commerce and travel.”
This has a subject (“It”) and a verb (“linked”), so it is a complete sentence (an independent clause). That means the punctuation in the blank must end the first sentence so a new sentence can start with “It.”
Match the punctuation to sentence type and structure
Now compare the choices:
- A question mark would turn the first part into a question, which it is not.
- An exclamation point would show strong emotion or excitement, which the tone here does not require.
- A comma would leave the next part (“It linked…”) attached to the first as one sentence, creating a comma splice (two complete sentences incorrectly joined by a comma).
The only punctuation mark that properly ends a factual statement and cleanly separates it from the next complete sentence is a period, so the correct choice is “an impressive feat.”.