I think it is the 3rd one because health problems at older age.
Answer:
A. Compounds contain fixed ratios of different elements.
Explanation:
Water always has this 2:1 ratio of hydrogen to oxygen. Like water, all compounds consist of a fixed ratio of elements. It doesn't matter how much or how little of a compound there is. It always has the same composition.
The right answer is the second one
Answer: Definition of reproductive system. : the system of organs and parts which function in reproduction consisting in the male especially of the testes, penis, seminal vesicles, prostate, and urethra and in the female especially of the ovaries, fallopian tubes, uterus, vagina, and vulva.
Explanation:
