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.

The results of huy's eye exam show that he is nearsighted. which explanation should huy expect to hear? "you need convex lenses to shorten the distance that light takes to focus in your eyes." "you need concave lenses to shorten the distance that light takes to focus in your eyes." "you need convex lenses to lengthen the distance that light takes to focus in your eyes." "you need concave lenses to lengthen the distance that light takes to focus in your eyes."

9. an object is moved from the outdoors, which is at a temperature of 100 ºf, to a room at a temperature of 70 º f. what happens to the object when it’s placed in the room with a lower temperature? the object gives off more energy than it absorbs until it reaches a new lower thermal equilibrium where the amount of energy absorbed and given off is the same. the object gives off the same amount of energy as it absorbs until it reaches a new lower thermal equilibrium where the amount of energy given off is greater than the amount of energy it absorbs. the object gives off more energy than it absorbs until it reaches a new higher thermal equilibrium where the amount of energy absorbed and given off is the same. the object absorbs more energy than it gives off until it reaches a new lower thermal equilibrium where the amount of energy absorbed and given off is the same.

What is the wavelength of an earthquake wave if it has a speed of 8 km/s and a frequency of 3 hz?