"who is responsible for coordinating the activities of several fire companies in a defined geographic area such as a district

A BATTALION CHIEF is responsible.

Explanation: In the Fire service, there is a command structure and they are as follows, (in ascending order): Probationary Firefighter, Firefighter, Driver Engineer, Lieutenant, Captain, Battalion Chief, Assistant Chief, and Fire Chief.

Each rank has their own special duties.

In the BATTALION, there are several fire stations and multiple fire companies. A battalion chief, is in charge of a battalion who is responsible coordinating the activities of several fire companies, officers and fire fighters in a district. The battalion chief are also known as district chief.

answer; ///the above statement is (true); //

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.