Which of these is a sign of an un healthy relationship?

Physical or emotional abuse.

Explanation:

A sentimental or couple relationship is one in which two people come together united by love and with a life project in common, such as raising a family or developing a life as a couple.

Generally, it is understood that everything that the couple accepts and the parties consent and tolerate must be respected. Thus, for example, it is how infidelity is accepted by open couples, among other examples.

But when the parties harm their partner or perform actions that the other does not want, it is understood that the relationship between them is not healthy. Thus, when there are cases of physical or emotional violence, or abuse of trust (such as infidelity), it is understood that said relationship does not run down the right lanes.

what effect does exercise have on the nervous system?

the answer is c.