Natural selection acts on populations through a specific trait. Which statement must be true about that trait?
The trait is the same for all organisms.
The trait is resistant to mutations.
Most forms of the trait have the same impact on survival.
The trait is passed on genetically to the next generation.

Question

Natural selection acts on populations through a specific trait. Which statement must be true about that trait? 
       The trait is the same for all organisms.
       The trait is resistant to mutations.
       Most forms of the trait have the same impact on survival.
       The trait is passed on genetically to the next generation.

anonymous · Answer

For natural selection to act, the trait must be heritable, which means it is genetic.