Penicillin is a drug that kills bacteria. Today, many bacteria are resistant to this drug. How does natural selection best explain this observation?
A. Penicillin causes some bacteria to mutate.
B. Some bacteria survive penicillin and reproduce.
C. Resistant bacteria cannot be attacked by penicillin
D. Resistant bacteria mutate more quickly than normal bacteria.

How is coal extracted from mountaintop removal mines? a. dynamite is used to create underground tunnels where miners go to extract the coal. b. dynamite is used to break apart rocks and then draglines are used to remove the broken rock and reach the coal. c. coal in mountaintops is extracted by digging strips in the landscape to reach the coal. d. placer deposits in mountain river bottoms are removed by

The energy produced as a result of this flow of electrons from atom to atom is called

This is a form of winter precipitation. it is frozen precipitation falling as ice pellets. snowflakes melt into raindrops as they pass through a thin layer of warmer air. the raindrops then refreeze into particles of ice when they fall into a layer of sub-freezing air near the surface of the earth. this precipitation is called a) hail. b) rain. c) sleet. d) snow.