"Creating fear in us" is a gerund verbal phrase. Option A is correct.
A gerund phrase always begin with a gerund,(an ing word), and may include other modifiers and/or objects. Gerund phrases always function as nouns, so they will be subjects, subject complements, or objects in the sentence. So, to put it simply, a gerund is a noun formed with a verb ending in ing. In this particular case the gerung in the sentence is the verb "creating;"(create+ing).
(A.) is your answer to the question
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!
