QUESTION $1$

Consider the following short argument:

I$\text{'}$m not a suspicious person by nature, but the truth has become clear to me now. Think about how difficult it is to get a plane to fly. We have pretty massive brains, and we didn't figure it out until pretty recently. Birds aren't what we think they are$--$they're alien creations sent to spy on us$,$ disguised as creatures that could have developed on earth. Think about it: they fly. We can't fly. As I said, we could not even build things that fly until recently. But birds were around way before we could figure out how to make things fly. So$,$ they were created by something much more intelligent than us$.$ Aliens. But why would aliens create these things and send them here? Well, isn't it obvious? They're curious$--$they want to see what we're up to$.$ More nefariously, they want to make sure we don't advance too much too quickly. They want to hold onto their power. So they sent spies. They made them look like creatures that could have developed on earth, so we wouldn't catch on$.$ And it worked.

$2.$ Some of us even take them into our homes. Clever, these aliens. They've had us all fooled for years and years...

Which of the following is the main conclusion of this argument?

A$.$ The truth has become clear to me now

B$.$ They $[$aliens$]$ made them $[$birds$]$ look like creatures that could have developed on earth, so we wouldn't catch on

C$.$ Bird are not what we think they are $-$ they're alien creations sent to spy on us$,$ disguised as creatures that could have developed on earth

D$.$ They $[$birds$]$ were created by something much more intelligent than us