Two nuclides A and B are isotopes. The nuclides B and C are isobars. All the three nuclides A, B and C are radioactive. You may then conclude that

A

the nuclides A, B and C must belong to the same element

B

the nuclides A, B and C may belong to the same element

C

it is possible that A may change to B through a radioactive decay process

D

it is possible that B may change to C through a radioactive decay process