A vision will not become a reality unless employees know and want to do their part. , as a function of management, is primarily associated with this aspect.

leading      

Explanation:

A vision will not become a reality unless employees know and want to do their part. Leading, as a function of management, is primarily associated with this aspect.  Leading involves the motivation of employees/subordinates into do the necessary parts in order to achieve the companies goals. A good leader should be able to translate the organizational goals into his/her subordinates personal goals, the subordinates should be motivated in order to pursue the organizations goals. Motivation could be in the form compensation or bonuses for exceeding targets.

saving account is right

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."