Answer:
50. Option B, lymph
51. Option A, through nonspecific and specific immunity
Explanation:
The yellowish fluid that carries disease-fighting cells is known as lymph. Produced by the liver and digestive system and from the interstitial fluid, lymph circulates its own system (lymphatic system) of vessels and nodes, transporting proteins, excess interstitial fluids, fats, and bacteria.
Lymphocytes, present within lymph, are a type of white blood cell, a type that has the aforementioned disease-fighting capability. When pathogens (e.g. bacteria) enter the body, these cells mount a response and create a memory of said response in case the body encounters this specific pathogen again down the line.
This immune system response can be called both the nonspecific and specific immunities. There are subtypes of lymphocytes, of which the two of the major subtypes are T cells and B cells. Upon recognition of a pathogen, the T cells produced by the thymus gland begin to attack the pathogen in a nonspecific manner, sending phagocytes, cytokines, and more of the immune system's products to the seize the pathogen. This nonspecific immunity can also be called cell-mediated immunity because it simply handles the pathogen by recruiting specialized cells innate to the body. The B cells mark the pathogen and produce antibodies, which "memorize" the instructions on how to combat this specific pathogen for the patient's lifespan. If and or when the patient is invaded by this pathogen again, their body knows exactly what to do and can surmount the pathogen swiftly. This specific immunity can also be called acquired immunity.
In short, lymph is the yellowish fluid with the disease-fighting cells of the immune system that protect the body from disease through nonspecific and specific immunity; options B and A, respectively.
