The diagram below shows a portion of DNA. The nucleobases adenine, thymine, cytosine, and guanine are matched together in base pairs, and the order of these base pairs makes a genetic code. Which describes the genetic code in a human? Different genetic codes appear in each different type of cell. Every human has the same exact genetic code. Genetic codes change frequently in reaction to external factors. A genetic code determines the physical traits of the body.

Lyme disease is caused by a bacterium transmitted to people by deer ticks. deer ticks are almost never born infected with the bacterium, but they can pick it up from feeding on an infected host in any of the tick's three successive stage of development: larva, nymph, adult. once infected, a tick remains infected through any subsequent developmental stages, but since a tick feeds on only one host in each stage, it follows that . people can be infected only by being bitten by a tick that is either in larval stage or in the nymph stage b. people cannot be infected by a tick that picked up the lyme disease bacterium in the adult stage c. it is not possible for a person to be infected by a tick that is in the nymph stage or by a tick that was infected with the bacterium while in the nymph stage d. people infected with the lyme disease bacterium cannot transmit bacterium to adult deer ticks e. only deer ticks that are adults can transmit the lyme disease bacterium to people