A 2- or 3-year-old child can answer correctly when asked if he or she is a boy or a girl; however, the child may believe that

A) people other than himself or herself are asexual.
B) people can change sex by changing their hairstyles or clothing.
C) there is no reliable way to determine other people's sexes.
D) people can change sex by changing their hairstyles or clothing and there is no reliable way to determine other people's sexes.

A 2- or 3-year-old child is aware of their own gender identity and can recognize others as male or female based on external physical characteristics such as hairstyle and clothing. However, they may not understand that gender is a biological characteristic that cannot be changed simply by changing one's appearance. Therefore, option B is the best choice as it reflects this understanding. Option A is incorrect as it implies that the child thinks everyone is the same as himself or herself, which is not true. Option C is incorrect as the child already knows how to determine other people's sexes based on external physical characteristics. Option D is incorrect as it combines the misunderstandings of both options A and B.