Explanation
The correct completion of the phrase "When the going gets tough, the tough get..." is:
D) Going
Explanation: The complete phrase is "When the going gets tough, the tough get going." This proverbial expression means that when faced with challenges or difficulties, strong or determined individuals do not give up or back down; instead, they become more determined and resilient. They take action and keep moving forward despite the obstacles or hardships they encounter. The word "going" in this context refers to the act of continuing with determination and perseverance.