Answer:
I'm pretty sure B. If that's wrong than it's D.
Explanation:
The predicate is researches , because it is an subject
The anwer is <span>Few airmen volunteered for positions as gunners.
</span><span>in The Death of the Ball Turret Gunner depicted the situation in World War II. You can see it from these lines:
</span><span><em>Six miles from earth, loosed from its dream of life, - </em>indicates that he's lonely
</span><span><em>I woke to black flak and the nightmare fighters. - </em>indicates that he held the position as gunners.</span>
