Which of the following uses an active voice?

Active voice is when the noun or object is the one that does the action.

^^^This is a bit confusing, so how I think about it is if a sentence uses any of the following words then it isn't using active voice:

-is

-was

-am

-are

-have been

-has

-will be

-being

A. She makes the most of the opportunities she’s given.

B. The dog show can be observed from the stands. <<< the "dog show" isn't the one that is really doing the observing, so this is using passive voice

C. The total number of participants was tallied up by the volunteers. <<<has the word "was" The participants were't doing the tallying, it was the volunteers, therefore it is in the passive form

D. The scholarships can be turned in as soon as this school year ends.

<<< The scholarships aren't doing the turning in, the people are, so it is using passive voice

answer A

Hope this helped

answer: do

the 'italicized phrase' is a noun clause that is used as a direct object.