Step 1: Understand the sentence.
The sentence talks about coordination inside a sales organisation. Coordination means that all sales people and managers work together towards one goal.
Step 2: Recall what a sales organisation must define.
A sales organisation groups sales tasks and people. For this to work, three things must be clear.
First, sales responsibility: who does which sales task.
Second, line authority: who can give orders to whom.
Third, accountability: who answers for the result.
Step 3: Fill the blank.
The blank follows 'sales responsibility' and 'line authority'. The third element in the textbook line is accountability.
Authority without accountability leads to misuse of power. Responsibility without accountability leaves nobody answerable for poor results.
Step 4: Why not other words.
Words like 'promotion' or 'commission' do not define work relationships. Only accountability completes the set of responsibility, authority and answerability.
Final Answer:
The missing word is accountability. Sales activities are well coordinated when responsibility, line authority and accountability are defined.