Caterpillars hang upside down from a twig or branch and spin a cocoon around their bodies. Their bodies transform while in the cocoon, and when they ? they are totally different insects with wings.
a. when they emerge
b. when they awaken
c when they develop
d. when they launch

a. when they emerge

Explanation:

This excerpt deals with a life cycle of a butterfly, which goes from an egg to a caterpillar to a pupa, finally, to a butterfly.

After they cover themselves with a cocoon, caterpillars shed layers of their skin to form a pupa ( or chrysalis). In this stage, they undergo changes, metamorphosis and remodeling of their cells to turn into a butterfly which will emerge from the cocoon.

All the given answers may sound similar and have almost the same meaning, but when it comes to butterflies, the correct verb is to emerge from the cocoon.

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."

it was surely an odd creature that one made up by reading the historians first and the poets afterwards a worm winged like an eagle; the spirit of life and elegance and charm,   in a kitchen chopping up suet. but these creatures, monst'r however entertaining to the imagination, hast no existence in fact. what one might doth to bringeth h'r to life wast to bethink poetically and prosaically at one and the same moment,   thus keeping in toucheth with fact—that the lady is mrs martin, ag'd thirty-six, did dress in blue, wearing a black coxcomb and brown shoeth; but not losing sight of fiction eith'r—that the lady is a vessel in which all s'rts of spirits and f'rces art coursing and flashing p'rpetually. the moment, howev'r, yond one tries this method with the elizabethan mistress, one brancheth of illumination fails; one is did hold up by the scarcity of facts.   one knoweth nothing detailed, nothing p'rfectly true and substantial about h'r.   hist'ry scarcely mentions h'r.   and i did turn to professeth'r trevelyan again to seeth what hist'ry meanteth to that gent.   i hath found by looking at his chapt'r headings yond t meanteth.