Maria has been married four times over a period of 22 years. none of her marriages lasted more than a few years. however, she was never married to more than one person at a time. in this scenario, maria has engaged in

Serial monogamy

Explanation:

Monogamy is a type of relationship where a person has only one partner during the course of their life.

In this case it is assumed that Maria does not have extramarital affairs during the course of her marriage.

When she remarries she remains faithful to her spouse during that time then divorces and remarries.

This is a form of serial monogamy.

the telephone is the answer