The endocrine system and the central nervous system may be linked in the etiology of depression through which substance?

According to the chapter Mad About Youabout sex differences in jealousy,

the evolutionary task of a woman is to (a) keep her mate from having a sexual affair (b) keep her mate from becoming emotionally involved with his mother (c) make sure her mate is constantly sexually satisfied (d) maintain her mate's investment and support for her and her children

Your friends Kumi and Hugh have a 6-month-old son, Joe. Kumi is a native speaker of Japanese and Hugh is a native speaker of English

They are thinking about raising Joe to be bilingual but they are wondering if there are any benefits or drawbacks to this. What can you tell Kumi and Hugh about the impact of bilingualism on language development? What will be an ideal response?