13. geologists can be employed as a. marine geologists b. petroleum geologists c. hydrogeologists d. environmental geologists e. all of the above

E. all of the above

Explanation:

Geologists -

are the scientist who studies matter in gaseous , liquid , solid state which constitutes the planet Earth and even other planets , are refered to as Geologists .

Geologist usually studies biology , chemistry , physics , and other sciences .

The people who are qualified as a Geologist , have the option to get employed as -

environmental geologists ,  hydrogeologists ,  petroleum geologists  , marine geologists .

Hence , the correct answer is E. all of the above