What is the correct grammar for the following sentence The groundhog who eats vegetables?

Answer 1

WHO is for people, you should use WHICH. (or THAT).

You use "that" to specify what you are talking about. (E.g. "That is the bear that I saw yesterday; it is limping.")

You use "which" when you are describing something, when it is already clear what you are talking about. (E.g. "The dog, which was wet and dirty…")

As for groundhogs… I do not know whether they normally eat vegetables.

If they do not, then "that" would specify the particular groundhog that has the unusual habit of eating vegetables, and "which" would note that this particular groundhog has the unusual habit of eating vegetables.

If groundhogs do normally eat vegetables, then "that" would be correct only if there was a group of unusual groundhogs that did not do this, and "which" would be used under similar conditions, but only in a pretty strange situation.

Having said all that… it seems clear that the sentence is telling us that groundhogs eat vegetables. Thus, "The groundhog" would mean the species… and "which" would be correct… and the sentence would be something like, "The groundhog, which eats vegetables, is a ground-dwelling hog that can be found in America."

Answer 2

The correct grammar for the sentence "The groundhog who eats vegetables" is a simple noun phrase that describes a specific groundhog that eats vegetables.