These questions appear to be multiple-choice answers. Please provide the original questions.

15. The normal human body temperature is 37°C.
The correct option is C.

$$\boxed{\text{C. 37°C}}$$

16. The heart is the organ that pumps blood.
The correct option is C.

$$\boxed{\text{C. Heart}}$$

17. The study of living things is called Biology.
The correct option is C.

$$\boxed{\text{C. Biology}}$$

18. Animals that eat only plants are Herbivores.
The correct option is C.

$$\boxed{\text{C. Herbivores}}$$

19. The Iris controls light entry into the eye.
The correct option is B.

$$\boxed{\text{B. Iris}}$$

20. An Earthworm is not a vertebrate.
The correct option is C.

$$\boxed{\text{C. Earthworm}}$$

21. The functional unit of the kidney is the Nephron.
The correct option is B.

$$\boxed{\text{B. Nephron}}$$

22. Respiration is the process that releases energy from food.
The correct option is A.

$$\boxed{\text{A. Respiration}}$$

23. The Kidney is the organ that removes urea.
The correct option is C.

$$\boxed{\text{C. Kidney}}$$