Every question is optional unless it says "(required)". You can skip anything. Nothing you submit is linked to you - no IP address, no name, no date or time. Be as honest as you are comfortable being.
In this survey, "abuse" means causing harm to an animal - injury, neglect, cruelty, or distress.
It does not mean sexual contact by itself. Some laws use the word "abuse" to describe any sexual contact with an animal, but that is not how it is used here.
When a question asks about abuse, it is asking about harm.