A. What causes these H-bonds to form? (Hint: Look at the charged regions.)

Hydrogen bonding is caused by the tendency of some atoms in molecules to attract electrons more than their accompanying atom. This gives the molecule a permanent dipole moment , it makes it polar, so it acts like a magnet and attracts the opposite end of other polar molecules.

Explanation:

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).