What is this excerpt mainly about? Any manmade objects that orbit around Earth and have no useful purpose are called orbital debris. This includes not working satellites, rocket bodies, debris created during spacecraft decaying and breakup, and mission-related debris. Mission-related debris consists of the items released during spacecraft operation, solid rocket fuel, items dropped by people in space, etc. About 23,000 objects over 4 inches in diameter have been recorded. Over one-third are in orbit now. They are tracked regularly by the U. S. Space Command. It is likely that there are more than 100,000 bits of debris between .4 and 4 inches in diameter. There are also tens of millions of particles smaller than .4 inch. Most orbital debris is within 1,250 miles of Earth’s surface.
30. What is this excerpt mostly about? *

a. There is a lot of space debris currently orbiting Earth.
b. Debris orbiting Earth is a hazard to NASA missions.
c. The amount of debris orbiting Earth is decreasing.
d. The U. S. Space Command watches space debris.