From Valence Bond Theory , What Is the Distinguishing Characteristic

From valence bond theory , what is the distinguishing characteristic between a sigma bond and a pi bond ?

A) A pi bond occurs when two orbitals overlap in a head to head fashion whereas a sigma bond results when two parallel orbitals overlap with a side-on interaction.
B) A sigma bond occurs when two orbitals overlap in a head to head fashion whereas a pi bond results when two parallel orbitals overlap with a side-on interaction.
C) Four electrons reside in a pi bond whereas two electrons reside in a sigma bond.
D) Two electrons reside in a pi bond whereas four electrons reside in a sigma bond.
E) A sigma bond results when both atoms involved in the bond donates one electron each towards the covalent bond whereas a pi bond results when one atom donates both electrons and the other atom donates no electrons towards the covalent bond.