Cattle and sheep are exposed to lead and zinc when these poisons are in the a. air that they breathe b .vaccinations from veterinarians c. dirt they walk and run on d. grass they eat and water they drink

Option D, grass they eat and water they drink

Explanation:

Most of the grazing animals including buffaloes, cows, and sheep have high level of lead and zinc in their blood or milk only when -

a) They graze is any farmland or grass land which is near to any lead/zinc smelter or factories that uses these two chemicals.

b) Or when these animals drink water from water bodies contaminated by lead or zinc released by industries.

Hence, option D is correct.

did you fail the test? xd

you know they are heterozygous for a trait because they have it as jj or jj.