Biology

Step 1: Understanding the Concept:
The question asks to identify the key physiological functions of calcium in the human body.
Step 2: Detailed Explanation:
Let's evaluate each function:

(A) Bone formation: This is the most well-known function of calcium. About 99% of the body's calcium is stored in bones and teeth, providing them with strength and structure. This is correct.
(B) Blood clotting: Calcium ions (Ca ) are an essential cofactor in the blood coagulation cascade, required for the activation of several clotting factors. This is correct.
(C) Muscle function: Calcium ions are crucial for muscle contraction. The release of calcium from the sarcoplasmic reticulum triggers the interaction between actin and myosin filaments, causing the muscle to contract. This is correct.
(D) Blood formation: Blood formation, or hematopoiesis, primarily requires iron (for hemoglobin), vitamin B12, and folic acid. While calcium is vital for the overall health of the body, it is not a direct or primary component in the synthesis of blood cells.
Step 3: Final Answer:
Calcium plays a key role in bone formation, blood clotting, and muscle function. Therefore, the correct option includes (A), (B), and (C).