Choose the sentence fragment. It should arrive late this afternoon.
Doctors often warn people about that.
The shoes by the front door are mine.
Everyone else in that part of the park.

its either

1. It should arrive late this after noon.

or

2. Doctors often warn people about that.

Explanation:

the 1st one isn't saying what "it" is, and the 2nd one doesn't explain what "that" is.