In relative dating, scientists determine the age of a fossil by... comparing the fossil's carbon to other carbon sources in the area.

measuring the amount of carbon-14 in the fossil.

comparing the fossil to other fossils found in rock layers in the same area.
measuring the half-life of the fossil.

Viruses can be transmitted through air, water, food, insect bites, and direct skin contact. once a virus gains entry into the body, it invades a host cell in order to? a. synthesize antibodies for defense b. deactivate the host cell's defenses c. access cell processes for reproduction d. metabolize host proteins and grow