Based on the expectation that two people in conflict should first try to arrive at a settlement together, organizations have a policy of making managers available to hear complaints. Typically, the first "open door" is that of the employee's

The correct answer to the following question will be "immediate supervisor".

Explanation:

The "immediate supervisor" seems to be the manager or supervisor who has already been appointed by both the sector to empathize with such a negative comment from workers during their working area, as well as to accept written complaints and operation them to either the correct stage throughout the technique or procedure.The very first "open window" is perhaps one of the individual worker's immediate supervisors, founded on the principle that both parties in dispute will first try and find a resolution collectively.

Thus the above is the right answer.