If you add 0 to anything, you do not have anything new when you are finished. A is an identity.
When you multiply 1 times anything, you do not get anything new. B is an identity
When you switch the order of two numbers and they are not affected by signs, then you are using the commutative property of addition. Nothing changes. C is an identity.
D is the problem child. Nothing I can think of right now will not change will you add 1 to it. If you can think of something that doesn't change when you add one to it, please put it in the comments. Otherwise, D is not an identity.
The first answer to your first question is option D, write down your equations in a notebook and start writing stuff down so you can learn well. Your doing great