I believe the answers to the sections of question 2 are:
A. "We" is who needs the umbrellas.
B. "Them" is the pronoun that replaces "umbrellas".
If you read each of these, or speak them, there is only one that suits the sentence correctly.
Go with the third one. Couldn't seems to fit pretty well there.
A: terribly: modifies old, an adjective
B: very smart: very modifies smart, an adjective
C; extremely modifies "slow", an adjective again
D: quickly modifies "hid" a verb - this is the correct answer!
Answer:
The ancient records of China and Japan are said to contain many allusions to the use of natural gas for lighting and heating.
B. A clown knocked down by a sandbag is the correct answer
