What is the distance between two alpha particles that are separated by 3.2 x 10⁻¹⁵ meters?

a) 6.4 x 10⁻¹⁵ m
b) 3.2 x 10⁻¹⁵ m
c) 1.6 x 10⁻¹⁵ m
d) 9.8 x 10⁻¹⁵ m