It's hot outside today.
It's is the contrasted form of it is and its is the possessive form *as it is without an apostrophe*.
For example:
The tree has lost all its leaves.
It's my birthday today.
The correct answer is A.<span>could not be heard above the voices in the hallway
</span>
B is a subject, C is an adverbial of reason, while D is an adverbial of manner.
Sarcasm is an ironic or satirical remark tempered by humor. Mainly, people use it to say the opposite of what's true to make someone look or feel foolish. For example, let's say you see someone struggling to open a door and you ask them, "Do you want help?" If they reply by saying, "No thanks. I'm really enjoying the challenge," you'll know they're being sarcastic. Sarcasm is all about the context and tone of voice, which is why it works better verbally. It's something you'll know when you hear it.
