A mutagen is a living thing that has undergone a mutation.
an agent that causes a mutation in DNA.
a mutation that has affected one gene.
any chemical that can poison living cells.

B)an agent that causes a mutation in DNA.

have a nice day

Explanation:

your a sped   no one cares

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c