Read the following passage and choose the best answer among A, B, C or D provided

Romantic relationships are a major developmental milestone. They come with all the other changes going on during adolescence - physical, social and emotional. And they're linked to a teenager's growing interest in body image and looks, independence and privacy.

Romantic relationships can bring lots of emotional ups and downs for a teenager - and sometimes for the whole family. The idea that the teenager might have these kinds of feelings can sometimes be a bit confronting for his or her parents. But these feelings are leading your child towards a deeper capacity to care, share and develop intimate relationships.

There isn't a ‘right age’ to start having relationships - every child is different. But here are some averages of when teenage relationships start. From 9-11 years, your child might start to show more independence from the family and more interest in friends. From 10-14 years, your child might want to spend more time in mixed gender groups, which might eventually end up in a romantic relationship. From 15-19 years, romantic relationships can become central to social life. Friendships might become deeper and more stable.

Many teenagers spend a lot of time thinking and talking about being in a relationship. In these years, teenage relationships might last only a few weeks or months. It's also normal for children to have no interest in romantic relationships until their late teens. Some choose to focus on schoolwork, sport, or other interests.

Câu 21 : According to the passage, romantic relationships among teenagers signal ________.

A. an important stage of their development.

B. the most serious emotional challenges.

C. the physical, social and emotional changes.

D. feelings of independence and privacy.