Plzzz anyone its easy but i dont understand

Hello there, 
wheel - used to travel one place to another - bc think about the cars that we drive, Its just rolling on wheels.

dog- used for herding and standing guard - because most dogs love their owners so they want to protect them, they can also look after some animals.

I'm 85% sure about these        /
                                              /
                                             V
   used for clearing forest- fire- because fire can almost tear down anything, and fire is already doing that to forests all around the world.

metal- used for plows and weapons- plows are what farmers use and they do stuff with crops, Also their metal, and so are the weapons we use today.

please tell me if I got these wrong

p.s. I like that song you were listening - wasted dreezy.

Is there a passage that comes with this question or should i know this right off the bat, because if it is, i probably have short term memory loss or college is too stressful