Sampling interval must be determined in random sampling

Correct Answer: C

Rationale: Systematic sampling requires a sampling interval (e.g., every 5th unit) to select from a list. 'Systematic,' is correct, per sampling theory (e.g., Lohr), ensuring regular selection. 'Simple,' uses pure randomness, no interval. 'Stratified,' divides by groups, not intervals. 'Cluster,' samples groups, not individuals systematically. The interval's role in systematic sampling's methodical approach makes C the precise answer.

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: Spermatogenesis is the full process of sperm formation, from spermatogonia to mature spermatozoa. 'Spermatogenesis,' is correct, per histology texts like Junqueira's Basic Histology, encompassing mitosis, meiosis, and differentiation. 'Oogenesis,' is egg formation. 'Spermiogenesis,' is the final differentiation phase, not the whole process. 'Spermatogonia,' are precursor cells, not the process. Spermatogenesis' comprehensive scope makes C the precise answer, covering all stages.

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.