Why did ptolemy have to introduce multiple circles of motion for the planets instead of a single, simple circle to represent the planet’s motion around the sun?

Because a planet travels faster or slower through the sky at different times. And plus, Mars, Jupiter, and Saturn appear to move BACKWARDS through the sky for part of every Earth year. It's very hard to make them all behave this way if each one is traveling in one simple circle.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.

pretty sure it's false