When the cell concentrates potassium within, against the natural tendency of matter, it is performing

Active transport requires energy when moving molecules against a concentration agent. It requires for specific membrane transport proteins. Only a certain type of protein can move a certain type of substance. 

The three main types of Active Transport are:
1) Sodium-Potassium Pump
2) Endocytosis
3) Exocytosis  

The answer would be d because x,y = male and x,x = female so x,y is male so xxy is male with a female trait!