Answer:
B. Passive
Explanation:
Identifying passive voice: such sentences usually consist of verbs like was, were, is, are, has, had, have, to be, may be and will be. In addition it has the past participle of an action verb e.g. words ending in –ed or –en, like were studied, will be considered, are being conducted, etc.
It is the semifinal, and the game is tied. The players challenge each other for the ball, and one player is tripped. The pressure is on, and the fans are screaming for a penalty. Will the referee do it?
The sclupture would be the appositive part. It is a noun too.

If two similar waves are traveling in the same medium, then they have same wave velocity. so we can infer that

Now, as per the formula ~ we know that :

Now, we can write it as :

And it's also given that frequency of wave A is 3 times that of frequency of wave B.
So, let's add the relation to our equation ~



So, choice C is correct ~