This statement about the giraffes is a logical fallacy called hasty generalization. The boy thinks that if one giraffe was friendly to him, that all giraffes are bound to do the same - he is generalizing something that doesn't have to be correct.
Well theres nothing really wrong with it. Maybe in certain places it can be questionable. But it's their bodies so whatever they want to do with it is their choice really.
The answer is A. relative. The sentence use the pronoun "that" which can be either a relative or a demonstrative. By analysing the sentence, we can see the pronoun was used to connect (relative) instead of to point at things (demonstrative).