A certain strain of bacteria used to be susceptible to penicillin. Today, that strain is resistant to penicillin. Which best explains this observation?
A. The bacteria needed to become resistant to survive.
B. The mutation rate in the bacteria population greatly increased.
C. The isolation of the strain caused it to become resistant.
D. A mutation occurred and was passed to future generations.

i think that d. wind is the answer.   i missed the question when i answered a. currents.

ans.

dna fingerprinting is defined as a process that determines the dna characteristics of an individual. these dna characteristics are unique among individuals as their fingerprints, so it is known as dna fingerprinting.

steps of dna fingerprinting includes extraction of dna from sample, amplification of dna, restriction digestion of amplified dna, and then analysis of dna by gel electrophoresis, respectively.

thus, the next step performed by the scientist is 'to cut the amplified dna (obtained by polymerase chain reaction) by restriction enzymes that cleave the dna into fragments and their analysis.'