13. which of the following is a key factor influencing the uptake of contaminants by ingestion:

a. contaminant concentration
b. carcinogenic potential
c. volatility
d. partition coefficient 1

Contaminant Concentration is the  key factor which influences the uptake of contaminants by ingestion

Explanation:

There are various ways in which individuals may be exposed to contaminants in environmental media .Below mentioned are some of the ways :

Ingestion refers to the  process of intake of food,water or any substance.Ingestion of contaminants can occur through intake of water (Ground water or surface water) or any food depending on the concentration of containment in that particular substance. Inhalation of contaminants: Individual can also inhale contaminants through  polluted air.Dermal contamination occur when an individual skin comes in contact with the contaminated air ,water,soil and other contaminated material