When Javier exercises, his muscle cells need more oxygen. Which would help Javier's muscle cells receive more oxygen? OPTIONS:
- decreasing his respiration rate
- increasing his perspiration rate
- increasing the rate his heart beats
- decreasing the rate his blood flow
A: increasing the rate his heart beats

Which of these objects is visible because it reflects light toward the eye? OPTIONS:
- burning candle
- flashlight bulb
- glowing campfire log
- shiny metallic balloon
A: shiny metallic balloon

A newborn kangaroo has the ability to crawl into its mother's pouch to drink milk. This is an example of OPTIONS:
- migration.
- an instinct.
- hibernation.
- a learned behavior.
A: an instinct.

The primary function of a doorbell circuit is to convert electrical energy into OPTIONS:
- sound.
- motion.
- radiant energy.
- chemical energy.
A:
sound.