I am thinking studying
1. of
2. in​

of

because in means inside of something and of mean to do some thing

hope you understand properly about it.

i believe the answer is: b. mr. head had a long, tube-like face with a rounded open jaw and a short depressed nose.

this is because in the un-revised sentence it said that mr. heads face was long and tube-like, and he had a rounded open jaw. this is not a very grammatically correct because of how it seems to drag on with the and, replaced with, with, makes it sound more fluent in the description.

c? not a 100% sure

explanation: