An equivalent is:
a) an equivalent is the amount of ion that has a 1+ charge.
b) 1 mole of an ionic compound.
c) 1 mole of any ion. the amount of ion that carries 1 mole of electrical charge.
d) the amount of ion that has a 1- charge.

The amount of ion that carries 1 mole of electrical charge

Explanation:

One equivalent: In reaction stoichiometry, the amount of one substance that reacts with one mole of another substance. This will often (but not always) be a 1:1 mole ratio.