This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to get rid of bats
Verify that it's bats you're dealing with.
The occasional rustling in the attic may just be an old water pipe or the sound of the house settling. Make sure you've excluded all other possibilities before you begin spending time and energy on a bat-removal project.

Possible answers: A. Keep a bottle of water on your way to work. Check your permit, if you have one, and make sure it's not already filled. B. The best way to tell that you have bats in your home is to see one with your own eyes or come across their tell-tale droppings. Consult a pest removal specialist or wildlife expert to determine what type of bats are commonly found in your area. C. Bats have long been kept out of bedrooms, but fallen ceilings can do little more than silence any sounds your friends may hear. Investigating bats without a simple eye-check should be safe, but prolonged exposure to bats can also cause serious health issues. D. If you encounter bats in your house, make sure to check to see if their flight routes or hunting patterns are clearly visible. If you have concerns about their behavior, consider organizing a swat squad to flush those stray bats down the toilet.
The answer is:
B.