Question

Many types of animals have internal skeletons. A large part of these animals' masses is located in their bones. As an animal grows, its skeleton grows. A growing animal must increase the size of its bones. To do this, the animal needs lots of calcium, an element important to the structure of bones. How can a growing animal get calcium to make new bone tissue?
A. by removing calcium from its bones B. by making calcium from other elements C. by consuming food that contains calcium D. by removing calcium from the air

Answer 1

The best answer is c. Removing calcium from its own bones would be counter productive, and many animals don't possess the ability to make calcium from other elements, or removing calcium from the air.

Hope this helps!