Performing a risky maneuver that required precision flying

[sherryL513]

hi, dear tutors, it is my first time to post a question here, but manhattan and Thursday with Ron has been great help to my gmat study. Just wanna say thanks a lot.

Back to my question re this problem. I wrongly choose A, could any of you pls help enlighten me of why A is wrong?

many thanks,
Sherry

[Sage Pearce-Higgins]

Glad to hear that. Answers A, B, and C are wrong because of a rule about modifiers. 'Performing a risky maneuver that required precision flying,' is an opening modifier and should be followed by the noun that it's modifying (i.e. the astronauts). This is an important rule to master, so check out the Modifiers chapter in the SC strategy guide.