Which sentence contains an adverb clause?

a.
once we unpack our suitcases, we will jump into the indoor swimming pool.

b.
we are traveling across the country to visit relatives in arizona.

c.
my family lives in boston, which often has much cooler weather.

d.
my cousin, who tells very funny jokes, will surely make me laugh.

An adverb clause consists of a group of words that are used as adverbs. This can be used to describe verbs, adjectives and even adverbs. Among the choices given, the correct answer is letter A. Once we unpack our suitcase, we will jump into the indoor swimming pool. The adverb clause in the sentence is, "Once we unpack our suitcase". 

Perpendicular line? no.