You may go for a walk if you feel _____ it.

The answer is like.

Explanation:

In the sentence "You may go for a walk if you feel _____ it," the correct word to fill in the blank is "like." This is because "feel like" is a common idiomatic expression in English used to express a desire or inclination to do something. The phrase 'feel like' is often followed by a noun or gerund (verb-ing form) to indicate what someone wants to do or is in the mood for. In this case, the structure is "feel like + gerund (going)," which correctly completes the sentence: "You may go for a walk if you feel like going for a walk." The other options - 'about', 'on', and 'for' - do not fit idiomatically or grammatically in this context.