What is it called when an environment has reach the highest number of organisms that it can support

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

Many organizations release indexes used to measure the development of the world's countries. as we learned in this lesson, these indexes measure many factors, from life expectancy to happiness. in your opinion, what are the three most important factors we can use to determine how developed a country might be? explain your answers in a few sentences.

Which factor affects the force of gravity between objects? check all that apply. direction distance mass shape time