According to Freud's psycho-sexual development theory, the stage in which…

Sigmund Freud's psychosexual development theory holds that personality forms through five sequential stages, each centered on a specific erogenous zone: Oral (birth to 1 year), Anal (1 to 3 years), Phallic (3 to 6 years), Latency (6 years to puberty), and Genital (from puberty onward). Unresolved conflict at any stage causes fixation, shaping adult personality traits; successful resolution allows psychosexual energy to mature toward adult sexuality.

The genital stage begins at puberty, when the sexual drive re-emerges and libido becomes centered on mature genital functioning. At this stage the individual's sexual interest shifts outward and matures into attraction toward the opposite sex, oriented toward adult romantic and reproductive relationships — exactly the adolescent attraction described in the question.

• Phallic stage (roughly ages 3 to 6): centers on a child's awareness of the genitals and the Oedipus/Electra complex — attachment to the opposite-sex parent, not romantic attraction to peers; occurs in early childhood, well before adolescence.

• Anal stage (roughly ages 1 to 3): centers on bowel and bladder control and the child's first experience of authority and self-control; has no connection to attraction toward another person.

• Latency stage (age 6 to puberty): sexual urges are dormant or repressed while the child focuses on social, intellectual, and skill development; attraction toward others is specifically absent during this stage.

Because adolescent attraction toward the opposite sex marks the onset of mature genital sexuality, the stage described in the question is the genital stage.