Which of the following is true concerning continental crust? a. it does not contain radioactive elements. b. it mostly contains heavier and denser minerals than the mantle. c. it efficiently transfers heat from the mantle to the surface. d.. none of the above

The mantle is more dense, so it can not B.
 Not even A , because the crust sure does contain naturally occurring radioactive material. Heat  is also not  efficiently transferred to the surface--most ground is cool,
so correct option is none is above that is D 
hope it helps

The answer is option a

The offspring will be blood type aa, bb, ab and oo or i