Question

organ where lymphocytes are synthesized, developed, and matured; organ where a special lymphocyte that aids the immune system is activated; organ in which macrophages break down old blood cells and bacteria or viruses; organ that acts as the first line of defense in the nasal and oral cavity; red bone marrow; thymus; tonsils

Explanation:

Step1: Analyze red bone marrow function

Red bone marrow is the site where lymphocytes (and other blood cells) are synthesized, developed, and matured. So match red bone marrow to "organ where lymphocytes are synthesized, developed, and matured".

Step2: Analyze thymus function

The thymus is where T - lymphocytes (a special lymphocyte aiding the immune system) mature and get activated. So match thymus to "organ where a special lymphocyte that aids the immune system is activated".

Step3: Analyze tonsils function

Tonsils act as the first line of defense in the nasal and oral cavity, trapping pathogens. So match tonsils to "organ that acts as the first line of defense in the nasal and oral cavity". (Note: The "organ in which macrophages break down old blood cells and bacteria or viruses" is the spleen, which is not one of the organs here, so we focus on the given organs.)

Answer:

• red bone marrow $

ightarrow$ organ where lymphocytes are synthesized, developed, and matured

• thymus $

ightarrow$ organ where a special lymphocyte that aids the immune system is activated

• tonsils $

ightarrow$ organ that acts as the first line of defense in the nasal and oral cavity