How does natural selection affect undesirable traits? select one of the options below as your
a. it increases them.
b. it has no effect .c. it eliminates them.
d. it decreases them.

C. It eliminates them 
This is because as time pass on the undesirable one will die because it could not compete against the desirable traits. As time pass on the weaker ones will die and the stronger will take over and will pass on their genes to the next generation. 

Size and shape of continents

The correct answer is a