According to the talk-test method of measuring exercise intensity, a person who is engaging in vigorous physical activity should be
a. able to talk during the activity.
b. able to sing during the activity.
c. unable to hear others talk during the activity.
d. unable to talk during the activity.

Which term defines one's age as measured by how well the body is working? chronological age biological age social age mental age

Which safe and legal options do teen parents have if they think they are not ready to be parents? check all that apply. leave the baby in front of someone's door. surrender the baby under their state's safe-haven laws. place the baby for adoption. release custody to the baby's grandparents. give the baby to a stranger.

Viruses use the host's machinery to make copies of themselves. however, some human viruses require a type of replication that humans do not normally have. for example, humans normally do not have the ability to convert rna into dna. how can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires? a) the virus causes mutations in the human cells, resulting in the formation of new enzymes that are capable of performing these roles.b) the viral genome codes for specialized enzymes not in the host.c) the virus infects only those cells and species that can perform all the replication roles necessary.d) viruses can stay in a quiescent state until the host cell evolves this ability.