Answer:
D. The half-life of Material 1 is 5 years more than the half-life of Material 2.
Step-by-step explanation:
As you can see in the graphs for material 1 to get to 50% it takes 30 years. for material 2 it takes 25 years to get to 50%. Therefor the halflife of material 1 is 5 years more than material 2