Please choose the correct answer to the 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?

Answer1: concentrated nutrients and a steep salt gradient Answer2: abundant shelter and concentrated nutrients Answer3: a steep salt gradient and shallow water Answer4: shallow water and abundant shelter

Answer format: answer1/answer2/answer3/answer4