Correct Answer: C

Rationale: Tofu is a plant-based source of protein that can provide a significant amount of protein to a person on a vegan diet. It is made from soybeans and is a versatile ingredient that can be used in various dishes to increase protein intake. Tofu is a good option for vegans looking to meet their protein needs. Eggs and fish are not suitable for a vegan diet as they are animal products. While leafy greens do contain some protein, they are not considered a significant protein source compared to tofu.

Correct Answer: D

Rationale: Cilia are not part of the body's secondary defense system. They are hair-like structures primarily involved in movement and transporting substances across cell surfaces, such as in the respiratory tract for debris and pathogen removal. However, cilia do not play a direct role in the immune response mechanisms characteristic of the body's secondary defense system. Macrophages, leukocytes, and T cells are immune cells that actively participate in the secondary defense system by targeting and eliminating pathogens.

Correct Answer: C

Rationale: Tofu is a plant-based source of protein that can provide a significant amount of protein to a person on a vegan diet. It is made from soybeans and is a versatile ingredient that can be used in various dishes to increase protein intake. Tofu is a good option for vegans looking to meet their protein needs. Eggs and fish are not suitable for a vegan diet as they are animal products. While leafy greens do contain some protein, they are not considered a significant protein source compared to tofu.

Correct Answer: C

Rationale: The correct answer is C: 26. The human foot consists of 26 bones, including tarsal bones, metatarsal bones, and phalanges. These bones collaborate to offer support, flexibility, and stability for various activities like standing, walking, and running. Choice A (6) is incorrect as it is too low for the number of bones in the human foot. Choice B (16) is incorrect as it underestimates the actual number of bones in the foot. Choice D (36) is incorrect as it overestimates the number of bones in the human foot.

Correct Answer: D

Rationale: Melatonin is the hormone produced by the pineal gland. It plays a crucial role in regulating the sleep-wake cycle and is instrumental in maintaining the body's circadian rhythm. Melatonin production is triggered by darkness and inhibited by light, aiding in signaling the body when it is time to sleep. Corticosteroid, oxytocin, and prolactin are hormones produced by other glands in the body and are not associated with the pineal gland. Therefore, they are incorrect choices for this question.