Scientists have detected an asteroid that is 700,000,000 km from Earth. About how many astronomical units is that?
0.5 AU
1 AU
3.5 AU
O 4.5 AU

Horizon a is also sometimes called a. topsoil b. subsoil c. bedrock d. weathered bedrock

Which of these describes nerve cells? a. specialized cells that protect the body from harmful bacteria b. specialized cells that maintain structural support c. specialized cells that send messages from one part of the body to another d. specialized cells that the body move freely and maintain flexibility

What is the most effective approach the government can take to keep the air clean? create and enforce regulations that limit fossil fuel burning by industries use funds to understand why smoke and mold are causes of outdoor air pollutants educate people about the threats to outdoor clean air from visible forms of air pollution modify regulations under the clean air act by including expensive options to reduce air pollution