Which sentence is an example of faulty parallelism?

a. The flowers my grandmother planted are azaleas, marigolds, and peonies.

b. My grandmother enjoys planting seeds, watering plants, and weeding the garden.

c. My grandmother not only planted a garden but also a bed of flowers.

Choice C is the answer. You can say that my grandmother planted not only a garden but also a bed of flowers or that my grandmother not only planted a garden but also planted a bed of flowers.

c. My grandmother not only planted a garden but also a bed of flowers.

Explanation:

Faulty parallelism is what we call in english when a sentence ennumerates or puts together terms that are not equally constructed, in the first two sentences you can see that the parallelism is well constructed because in the first one the flowers are listed and have the same form in all the sentence, and in the second you can see that they use the verb in gerund to make a reference to an activity that the grandmother enjoys, but in the last one you have two different kinds of nouns, one being the garden, the other the bed of flowers which is a metaphor, if you are using a metaphor to sound more romantic, the sentence should say "My grandmother didn't plant a garden, she planted a bed of flowers".