Final answer:
Brad should use the Competing resolution style to assert his own interests in the situation.
Step-by-step explanation:
Brad should use the A) Competing resolution style.
Competing style is characterized by a high concern for self and low concern for others. In this situation, Brad wanted the regional manager position and was willing to assert his own interests, even if it meant disregarding the interests of others, including Tom.
By applying for the position himself, Tom knew that Brad would back down and not compete with him, as Brad tended to be accommodating and would prioritize the needs and desires of others over his own. Therefore, the strategy Tom used to ensure Brad's compliance was to compete with him for the position.