Which word correctly completes the sentence? made this beautiful sculpture? a. whose b. who c. whom

It's B because Who fits in the sentence: Who made this beautiful sculpture because your asking which person made this.
Hope this helps!  :)

1. The answer is d) When you make friends, you should stay in touch, smile, and be nice.
Parallel structure refers to repetition of a certain grammatical form within a sentence, suually being done by comparing the idea into a grammatical pattern in order to create parallel construction.

2 the answer is A. a) In the mornings, I take a shower, getting dressed, and go to school.
This part of sentence is not parallel: 
. . . I take a shower, getting dressed,  . . . 
It should be written as :
. . .I take a shower, get dressed, . . .

3. I believe the answer is B. friendly to others.
The other three options beside this contains verb-ing that not only ruin the parallel because the initial comparison only contain adjectives  (smart and responsible)

4. the answer is D. thought about the book.
as we see in this sentence
He was sitting, reading,  . . .
The paralel was iniitated by verb-ing. Therefore it need to be followid by another verb-ing, such as planning a dinner, considering his options, or eating a sandwhich