Which focus question is the author trying to answer?
c
Read the introduction from a science website
Electromagnetic force sounds very complicated, but I
wanted to understand how it works My experiment allowed
me to create my own electrical field using a nine-volt
battery, an iron nail, and some paperclips This experience
helped me understand electromagnetism and the way it
works
O How does a nine volt battery work?
O How does electromagnetic force work?
O How much electricity is stored in a battery?
O How much iron is contained in paperclips?

The correct answer is: How does electromagnetic force works.

Explanation:

In this excerpt, the author tries to understand how does electromagnetic force works.

We can conclude that from some statements he uses to explain his experiment.

e.g. Electromagnetic force sounds very complicated, but I  wanted to understand how it works.

e.g. This experience  helped me understand electromagnetism and the way it  works.

the correct answer would be:  

a. adverb phrase

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."