Aresearch study attempts to describe the relationship between self-esteem and birth order position by measuring self-esteem for each individual in a group of first-born boys, and then comparing the results with self-esteem scores for a group later-born boys. this study is an example of the strategy.

Non-experimental.

Explanation:

A non-experimental strategy of research is that which the variable or group of subjects can't be manipulated by the experimenter. In this case, the researcher can't manipulate the fact that they are first-born or later-born or not.

intimacy, passion and commitment are the components of a interpersonal relationship emphasized in the triangular theory of love by robert sternberg.

the triangular theory of love says love can be comprehend as this componest form the vertices of a triangle.  

intimacy relates to feelings such as of closeness and connection;

passion relates the drives that brings people together, as physical attraction.

commitment relates to the being in a long-term relationship.