Correct option: AExplanation:Thymus gland produce mature T cells or T lymphocytes, which fights against infections in the body. These with B cells provide primary protection to the body from any bacteria, virus or foreign antigens. If any damage occurs to thymus gland in a child, it will effect the immunity and growth of the body and the child will become more prone to diseases. It will also effect the T cell production and lead to loss of cell mediated immunity in the body. A reduction in the haemoglobin content in blood leads to Anemia. A reduction in the amount of plasma proteins leads to Hypoproteinemia.Loss of antibody mediated immunity or humoral immunity leads to loss of B cells.Thus, Option A is correct.