Question 21·Hard·Form, Structure, and Sense
Bound for Mars on a nine-month journey, _____
Which choice completes the text so that it conforms to the conventions of Standard English?
For questions with an introductory phrase followed by a comma (especially ones starting with an -ing or -ed word like "Bound" or "Traveling"), immediately identify what that modifier should logically describe, then make sure the very next noun phrase in the answer choice is that thing. Eliminate any options where the opener ends up describing the wrong subject or an illogical one (like an action instead of a person/thing), and prefer the choice that is both grammatically correct and clear in meaning, often in a concise, active-voice structure.
Hints
Focus on the introductory phrase
Concentrate on the words before the comma: "Bound for Mars on a nine-month journey." Think about what kind of word or phrase this is and what it needs to describe.
Ask who is actually traveling to Mars
Ask yourself: who or what is literally on the nine-month journey to Mars? The word or phrase that answers this question should appear right after the comma.
Look at the first noun in each answer choice
For each option, identify the first noun phrase after the comma (for example, "mission control," "the spacecraft"). Decide which one makes the most logical sense as the thing that is "bound for Mars."
Check for awkward or illogical meanings
Read each completed sentence in your head. If it sounds like something that cannot realistically be "bound for Mars" (like an Earth-based group or an abstract action), eliminate that choice.
Step-by-step Explanation
Identify the introductory phrase and what it must modify
The sentence begins with the phrase:
"Bound for Mars on a nine-month journey, _____"
This is a participial phrase (it starts with a past participle, "Bound") that functions as a modifier. By rule, this kind of opening modifier must clearly describe the noun that comes immediately after the comma.
Decide who or what is actually “bound for Mars”
Ask yourself: Who or what is literally traveling to Mars on the nine-month journey?
- Is mission control (on Earth) bound for Mars? No.
- Is an action like "continuous monitoring" bound for Mars? No.
- Are life-support systems themselves the traveler, or is it the whole spacecraft?
Logically, it is the spacecraft that is on a journey to Mars.
Check the subject at the start of each answer choice
Now look at what comes right after the comma in each option:
- A) mission control monitored the spacecraft’s life-support systems continuously.
- B) the spacecraft carried a crew that continuously monitored its life-support systems.
- C) continuous monitoring of the spacecraft’s life-support systems was carried out by mission control.
- D) the life-support systems of the spacecraft were continuously monitored by mission control.
Only one of these starts with the noun that is actually bound for Mars: the spacecraft.
Choose the option that matches grammar and meaning
The correct sentence must make the opening modifier clearly and logically attach to the subject:
"Bound for Mars on a nine-month journey, the spacecraft carried a crew that continuously monitored its life-support systems."
This version correctly attaches the modifier to "the spacecraft" and uses a clear, active structure, so the correct answer is “the spacecraft carried a crew that continuously monitored its life-support systems.”