The largest lymphoid organ in the body is the

Correct Answer: B

Rationale: The spleen, located in the upper left abdomen, is the largest lymphoid organ, filtering blood and mounting immune responses. 'Spleen,' is correct, per anatomy references like Gray's Anatomy, outweighing other lymphoid structures in size and function. 'Thymus,' is smaller, primarily active in T-cell maturation during youth. 'Tonsils,' are minor mucosal lymphoid tissues. 'Lymph nodes,' are numerous but individually small. The spleen's substantial mass (about 150-200g in adults) and dual role in immunity and blood filtration distinguish it, making B the precise answer, reflecting its prominence in the lymphatic system.

Correct Answer: C

Rationale: Fat-soluble vitamins dissolve in lipids, stored in body fat. 'Vitamin C,' is correct as the exception, being water-soluble, excreted in urine, per nutrition texts (e.g., Gropper). 'Vitamin A,' 'Vitamin D,' and 'Vitamin K,' are fat-soluble, absorbed with dietary fats. Vitamin C's hydrophilic nature, vital for collagen, distinguishes C as the accurate answer.

Correct Answer: D

Rationale: The large intestine includes caecum, colon, rectum, and anal canal. 'Duodenum,' is correct as the exception, part of the small intestine, per anatomy (e.g., Moore). 'Caecum,' begins the large intestine. 'Colon,' is its main segment. 'Rectum,' stores feces. Duodenum's small intestinal role distinguishes D as the accurate answer.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.