Genetic counselors work mostly with 1 school counselors.
2 researchers in genetic engineering.
3 elderly adults who live in care facilities.
4 couples who are planning to have children.

couples who are planning to have children

Explanation:

i think its the first one

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.