What happens to the half-life and mass of reactants broken down during a nuclear decay reaction?

a) the half-life of reactants in a nuclear decay reaction remains constant over time, but the mass of reactants that are consumed decreases.

b) the half-life of reactants in a nuclear decay reaction increases over time, and the
mass of the reactants that are consumed increases.

c) the half-life of reactants in a nuclear decay reaction decreases over time, but the
mass of the reactants that are consumed stays the same.

d) the half-life of the reactants in a nuclear decay reaction remains constant over time,
and the mass of the reactants that are consumed stays the same.