The number of bonded pairs of in a covalent bond equals the bond order.

The number of bonded pairs of electrons in a covalent bond equals the bond order.

For example:
In molecule of hydrogen (H₂), bond order is 1 (H-H), because there is one pair of electrons between hydrogen atoms.
In molecule of oxygen (O₂), bond order is 2 (O=O), because there are two pair of electrons (4 electrons) between oxygen atoms.
In molecule of nitrogen (N₂), bond order is 3 , because there are three pair of electrons (6 electrons) between nitrogen atoms.

C) the increase in atmospheric pressure pushes the walls of the balloon outward thus making it  is the answer.hope i you.

Ithink the answer is d