Coordinating or correlative sentences​

Conjunctions

What is a correlative conjunction?

As suggested by their name, correlative conjunctions correlate, working in pairs to join phrases or words that carry equal importance within a sentence. Like many of the most interesting parts of speech, correlative conjunctions are fun to use. At the same time, there are some important rules to remember for using them correctly

Explanation:

i've read it so how can i ?

the answer is b. the tracer looks harmless in flight, but the pilot’s bitten lips and white knuckles suggest how dangerous it can be.