According to dunphy (1963), the second step in the sequence of male–female relationships during childhood and adolescence is:

According to Dunphy (1963), the second step in the sequence of male–female relationships during childhood and adolescence is a loose association of girls and boys, with public interactions within a crowd. Dexter Dunphy’s classic study of Australian adolescent cliques suggests that cliques prepare adolescents for the hetero-social world. The first step are groups of friends, exclusively one sex or the other .

A loose association of girls and boys, with public interactions within a crowd

Explanation:

As regards the development of romantic attraction in adolescents , Australian researcher Dexter Dunphy outlined the four steps of male-female relationships in childhood and adolescence, from asexual to active. The first step involves groups of friends, exclusively one sex or the other; the third includes smaller mixed groups of  the advanced members of the crowd; while the last step deals with the constitution of couples, with an intimately close relationship.

the answer to your question is,

d. when a child was born.

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