Answer:
B.
Step-by-step explanation:
The example where we can see three beats in each measure is B.
In the first measure, we have a quarter note, two eighth notes, and another quarter note. That is three beats (1 + 1 + 1).
In the second measure, we have one half note and one quarter note. That is three beats as well (2 + 1).
So, each eighth note is half a beat long, each quarter note is one beat, while a half note is two beats long.