Which form of relationship is most common among adults in their early twenties? marriage or legally recognized domestic union romantic relationships that don’t involve marriage friendships only promiscuity

Many adults in their early twenties do choose to get married. However, in the world today it is more common for young adults to live as if married without actually taking the vows. So, your answer is legally recognized domestic union relationships that don't involve marriage. This is called Con-habitation.

the answer would be a." don't hit a home run when the game is tied"

b) the heart is a pump made of muscle and that is difficult to grow in the lab.