Answer: A) Condujo
Step-by-step explanation: The correct answer is A) Condujo, because, if we use the other words, we will get:
With B) Marcos conduje su carro nuevo - Marcos I drove his new car.
Doesn't make sense
With C) Marcos condujiste su carro nuevo - Marcos you drove his new car.
Doesn't make sense either
With D) Marcos conduzco su carro nuevo - Marcos I drive your new car.
Still doesn't make sense
Now, with the correct answer
With A) Marcos condujo su carro nuevo - Marcos drove his new car
Does make sense