Answer: All of the above choices are correct.
Explanation:
The major role of the immune system of the body is to protect the body against the attack of the foreign agents like bacteria, virus and fungi and also to prevent the entry of foreign materials like pollen, dust particles and others. The immune system does the surveillance of body by checking the invasion of the foreign agents into the body and protecting their impact on the body. The white blood cells are phagocytic in nature, they engulf the foreign particles and causes their destruction.
