Scar-like tissue that forms between two membranous structures and causes pain defines which of the following?

Each year in the United States, an estimated ________ of hazardous materials are shipped via road, rail, and pipelines

A) 8 million tons B) one hundred thousand pounds C) 4 billion tons D) 2 billion pounds

1. _____ is/are the main cause of asthma attacks in the dental office.

a. Illness b. Medications c. Allergens d. Anxiety