In a Hydrogen Fluoride (HF) Molecule, a Hydrogen Atom and a Fluorine

In a hydrogen fluoride (HF) molecule, a hydrogen atom and a fluorine atom are held together by a polar covalent bond. Which of the following best explains why this bond is polar?

A) the large difference in the atomic radii of hydrogen and fluorine atoms
B) the large difference in the atomic masses of hydrogen and fluorine atoms
C) the large difference in theelectronegativities of hydrogen and fluorine atoms
D) the large difference in the number of electrons of hydrogen andfluorine atoms