Which of the following reasons may support the tendency for many human females to show a preference for having only a few sexual partners?

A) Females have more parental investment than men.
B) In order to maximize the probability of a surviving offspring, the female must carefully carry and then care for the offspring.
C) The risk involved in bearing each offspring is much higher for women.
D) All of the above.

All three options mentioned in the question can support the tendency for human females to show a preference for having few sexual partners.

A) Females have more parental investment than men, which means that females contribute more to the upbringing and nourishment of an offspring. This is true in most cases, and it leads to the fact that females tend to be more selective than males when it comes to choosing a mate.

B) To maximize the likelihood of producing successful offspring, females must carefully carry and then care for their offspring. This process requires a significant amount of time and energy. Hence, they usually give birth and rear only a few offspring.

C) The risk involved in bearing each offspring is much higher for women. Pregnancy comes with various physical and physiological changes, and there is always a risk of complications during pregnancy, delivery, and postpartum care. Therefore, females tend to be more cautious and choosy in selecting a sexual partner.

Thus, all of the above factors play a role in explaining why human females may prefer having only a few sexual partners.