Hassall’s corpuscles are found in
(a)Thyroid
(b)Thymus
(c)Adrenal
(d)Pineal

Hint: It is a specialized lymphoid organ of the body's lymphatic system which is an important part of the immune system. It is present in the upper front part of the chest just behind the sternum which undergoes involution with age.

Complete answer:
Hassall’s corpuscles are also known as thymic bodies. They are concentric corpuscles composed of eosinophilic epithelial reticular cells arranged in concentric layers. They are considered as a distinguishing feature of the medullary area of the thymus. The concentric corpuscles are composed of a central granular core and an epithelioid capsule. Each corpuscle measures a range of 20-100 microns in diameter and grows in diameter with increasing age.

Additional Information: -As the Hassall’s corpuscles grow in size with age, they represent the involution of the thymus.
-The thymus develops at birth and grows to its maximum capacity till puberty, once puberty is reached, it undergoes involution speedily, and then it completely disappears about 65 yrs. of age.
-The thymus consists of the outer cortex and inner medulla, the epithelial cellular network is coarser in the medulla as compared to the cortex. The cortex is made up of immature T-cells (thymocytes), supported by a dense network of epithelial reticular cells.
-As the Hassall’s corpuscles grow in size, the area of the cortex diminishes into an external ring appearance.
-Other cells of the immune system are also present in the thymus, this includes macrophages, dendritic cells, b- lymphocytes, eosinophils, and neutrophils.
So, the correct option is ‘Thymus’.

Note: The immune system of the body consists of bone marrow, thymus, spleen, lymph nodes, tonsils, and mucous membranes. Bone marrow and thymus are the primary lymphoid organs and the other organs are the secondary lymphoid organs.
The spleen is the largest lymphatic organ in the human body.