a) pineapple

Pumpkins and pineapples are both fruits, as redwoods and maples are both trees.

Assuming that everyone agrees that "birch" is least right, I'm trying to come up with some logic whereby beet could be an option. Vegetable, grows below ground, all three can be propagated by seed, pumpkin leaves are inedible, neither beets nor pineapples have viny growth. Um, can't do it. Did the book seriously say that beet was the better answer?