The Relationship ,Where a Is the Mass Number of a Nucleus and a Nucleus

Multiple Choice

The relationship
,where A is the mass number of a nucleus and r is it radius,implies which of the following about nuclei?

A) Nuclei are cubic.
B) Different nuclei have the same density.
C) Neutrons in nuclei attract each other even though they have no charge.
D) Nuclei tend to have the same ratio of protons to neutrons.