Final answer:
John is using the autocratic leadership style.
Step-by-step explanation:
John is using the autocratic leadership style. In this style, the leader maintains strict control over planning and decision-making, insisting on determining the direction and outcome of all discussions. They issue orders and assign tasks without much input or feedback from group members. This leadership style can be effective in situations where quick decisions need to be made or when there is a need for centralized control.