question... What harms the respiratory and circulatory systems?
Options:
- (A) oil
- (B) rain
- (C) sulfur
- (D) cars
- (E) tires
- (F) coal
- (G) tar
- (H) bicycles
answer... Air pollution harms the respiratory and circulatory systems. Cars are a significant source of air pollution. Cars harm the respiratory and circulatory systems.
The answer is (D)

question... Some viruses can what?
Options:
- (A) fret
- (B) harm
- (C) damage
- (D) grow
- (E) expand
- (F) discover
- (G) visit
- (H) kill
answer... Some viruses can cause cancer. Skin cancer can kill. Some viruses can kill.
The answer is (H)

question... What may be stored in sedimentary rock for millions of years.
Options:
- (A) Sand castles
- (B) Chemical energy
- (C) heat energy
- (D) Millions of dollars.
- (E) A fuel source.
- (F) Energy.
- (G) In sediment
- (H) Stored animal fur.
answer...
Carbon may be stored in sedimentary rock for millions of years. Carbon is the fuel source. A fuel source may be stored in sedimentary rock for millions of years.
The answer is (E)