Yeah it seems like A is the right answer to me
It's in passive voice.
A good rule of thumb for cases like this is that if it has any variation of the verb "to be" (is, was, were, etc.) it's passive voice.
If you wanted to switch it to active voice you need to get rid of "is", and this is usually done by switching the subject and the object (so while in the original sentence, the race car is the doing the verb, to switch it you'd need to make the sixteen-year-old boy be the one doing the verb). This new sentence would be something like:
The sixteen-year-old boy drove the racecar
Researching is the best answer
