Answer:
C. The police officer gave a ticket to the truck driver.
Step-by-step explanation:
The subject police is doing the verb - "gave" to the truck driver. And the use of "by" towards the end of the sentence is not valid in active voice. The subject-verb relationship changes in the passive voice. So, while the other three options (A, B and D) all put the subject "police officer" at the end of the sentence, that means it is already in the passive voice, added with the use of "by" in these sentences. So, the correct sentence that is in the active voice is option C.