human
Question: Estuaries are called "the nurseries of the sea" because many species lay eggs and develop their young in estuaries. Which two features of estuaries support this role most?

Choices:
A) concentrated nutrients and a steep salt gradient
B) abundant shelter and concentrated nutrients
C) a steep salt gradient and shallow water
D) shallow water and abundant shelter
gpt
The correct answer is 1: abundant shelter and concentrated nutrients.