Write the next sentence in the following story.

How to care for newborn hamsters
Assess the parents' risk factors.
Hamsters reach sexual maturity as young as 6 weeks old, though it is not advisable to let them mate at this age. A female should be at least 8-10 weeks old before mating, and males 10-12 weeks old.

Pick from:
1). If they are older, reduce the amount of activity and expectations (sex to avoid unwanted pregnancy) during this age. These factors can range from poor appearance to poor behavior.;
2). The mother will have the easier time mating if she has more feces or is nursing, especially at this age. Consider the mother's inclination to mate.;
3). Once a hamster reaches 12 months of age, it should no longer be bred, as health risks skyrocket. The average hamster lifespan is 18-24 months.;
4). However, this is less important for everyone who plans to breed a single hamster. Pick a cage that fits your hamsters' species.;. The answer should be
3).