Based on the text interview study reporting on first ejaculation, what word best characterizes boys' reaction to this landmark pubertal "event"?

The correct word is: Secretive.

Explanation:

According to research in developmental psychology, boy's reaction to their first ejaculation, which generally occurs around 11-13 years of age, is generally associated with the word "secretive" for multiple reasons.

Boy's tend to keep quiet about their first ejaculation because that event is associated with "masturbation" and at that age that behavior is usually taboo for them, causing them to reserve the event for themselves.

In conclusion, the word that best characterizes boy's reaction to their first ejaculation is "secretive".