What are hydrogen bonds caused by?

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.

the answer is c) an oak tree

dude i stopped reading after the first 7 words but hey you seem real smart thats awesome have a great day