1. The words bin and bean, rot and rat are examples of . (homonyms is not the right answer) 2. Depending on their area of origin, whales can communicate in various . (ways and methods is not the right answer)

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