In which of the following sentences is the word its used correctly? a. the problem with the lawn mower is that its old. b. the monster reared its head at the tourists. c. when trying to catch fish, its important to be patient. d. its easy to learn to play the guitar, if you're willing to practice.

The correct answer choice is answer choice B, The monster reared its head at the tourists. Many people do not understand the difference between its and it's.

Its - possessive form of it
It's - contraction meaning 'it is'

When trying to figure out whether to use 'its' or 'it's', ask yourself if the sentence makes sense when you substitute 'it is'. If it does, then use 'it's'. If it doesn't, use 'its'.