Updated: Question in XAT 2012 Question Paper with Answers

A question in XAT 2012 Question Paper with Answers has been updated:

Which of the following sentences is grammatically incorrect?

1. Bats have the ability of flying in the dark, if it does not rain.
2. Bats cannot fly in the dark if it rains.
3. Bats are able to fly in the dark.
4. Bats can fly in the dark
5. Bats have the ability to fly in the dark.