Which of the following is not one of the four organs of the lymph system? a. Spleen b. Thymus gland c. Tonsils d. Bone Marrow

To determine which option is not one of the four main organs of the lymphatic system, let's first identify the primary organs commonly associated with this system.

1. Identifying the Main Organs of the Lymphatic System

The key organs of the lymphatic system include:

• Spleen: filters blood and helps in immune response.
• Thymus gland: important for the maturation of T-cells.
• Tonsils: act as the body's defense mechanism against pathogens entering through the mouth and nose.
• Lymph nodes: filter lymph and are pivotal in immune functions.

2. Analyze the Options

Now, let’s evaluate each of the answer choices:

• a. Spleen: This is a lymphatic organ.
• b. Thymus gland: This is also a lymphatic organ.
• c. Tonsils: These are indeed considered lymphatic organs.
• d. Bone Marrow: While it plays a vital role in the production of lymphocytes, it is not traditionally classified as one of the primary organs of the lymphatic system.

Final Answer

The correct option, which is not one of the four organs of the lymph system, is d. Bone Marrow.