Answer:
A. adjacent.
Explanation:
The given sentence presents a statement where the speaker is talking about his car that is next to a tall tree. And with that, we can easily assume that the tree and the car are right next to each other.
The synonym for that can be "adjacent" as adjacent means something that is right next to the other thing, or being next to each other. So, it makes the sentence as "the two are adjacent to each other.
