The correct option is C Excretion
The excretory organ of cockroach is the malpighian tubules. It is mainly involved in the secretion of metabolic waste and osmoregulation. They lie freely in the hemolymph. The distal parts of the tubules extract inorganic ions, uric acid and amino acids by active transport and water by diffusion from the surrounding hemolymph.
Therefore, the correct answer is option C.