New forms of drug-resistant bacteria can evolve quickly because
a
when a drug kills most of the bacteria, the ones left to breed are those that have a natural resistance to the drug.

b
when scientists genetically engineer bacteria they use natural selection.

c
scientists use extinction to selectively breed bacteria.

d
a drug causes mutations in the bacteria, leaving only mutated bacteria left to breed.

A.

because this is the correct forms to thr bacteria

0 because theres a difference between pickled peppers and peers.

-hope this : -/

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: