The correct option is A Contractile vacuole
Amoeba is a unicellular organism that are usually found in water bodies such as ponds, lakes and rivers. Most amoeba are characterized by the following features, nucleus that stores the genetic information, cytoplasm acts a medium in which all the cell organelles are suspended, pseudopodia helps in engulfing the food particles, cell membrane acts as a channel for transportation and the contractile vacuole helps in excretion of excess water and cellular waste.