Which one among the following is responsible for blood coagulation?

The correct option is D Platelets
Platelets are extremely small and disc-shaped. They participate in the blood clotting process.
Plasma is pale yellow, clear and slightly alkaline fluid. This contains 90-92% water, 6-8% proteins and 1-2% inorganic salts.

Red Blood Cells(RBCs) are small, circular, enucleated cells. They appear red due to hemoglobin and oxygen dissolves in blood due to hemoglobin.
White Blood Cells(WBCs) are large, nucleated and colorless cells. They attack the pathogens entering our body and protect us from the microbial diseases.