Women have a tendency to retain water during part of the menstrual cycle because estrogen mimics the action of what?

A. Two haploid (n) cells; four haploid (n) cells: At the end of meiosis I, the result is two haploid cells, each with half the number of chromosomes of the original cell. At the end of meiosis II, these two haploid cells divide again to form a total of four haploid cells.

B. Two diploid (2n) cells; one haploid (n) cell: This option is incorrect because meiosis I produces two haploid cells, not diploid cells, and meiosis II produces four haploid cells, not one.

C. Two diploid (2n) cells; four haploid (n) cells: This option is incorrect because meiosis I does not produce diploid cells; it produces two haploid cells. At the end of meiosis II, the result is four haploid cells, which is correct, but the description of meiosis I is incorrect.

D. Two haploid (n) cells; one diploid (2n) cell: This is incorrect because meiosis I results in two haploid cells, and meiosis II results in four haploid cells, not one diploid cell.

A. Surfactant reduces surface tension in the alveoli, aiding in lung expansion, but it does not directly stimulate breathing.

B. CO2 accumulating in the infant's blood: The accumulation of CO2 in the infant's blood is a significant stimulus for the first breath after birth. High levels of CO2 trigger the infant's respiratory centers to start breathing.

C. Prostaglandins are involved in labor and delivery but do not directly stimulate breathing in the newborn.

D. An increased O2 level in the infant's new environment: Increased O2 levels do not directly stimulate breathing; rather, the accumulation of CO2 is the primary stimulus.