Solution

The lymphoid organs are part of our body's immune system that are of two types: primary and secondary.
Primary lymphoid organs (bone marrow & thymus) are involved in the production of special immune cells called lymphocytes.
Secondary lymphoid organs (spleen, lymph nodes, mucosal-associated lymphoid tissue) provide the environment for the proliferation and maturation of cells involved in the adaptive immune response, for filtering and trapping antigens.
The spleen is the largest lymphoid organ in our body. It is located under ribs on the left side and above the stomach.

So, the correct answer is option C.