Explanation:

Correct option 4: 

 Proactive: Taking initiative or action in advance to address an expected challenge.

 Option 1: Heedless: This means showing a reckless lack of care or attention. It's not similar to proactive.

 Option 2: Short-sighted: This involves not considering the future implications, opposite of planning ahead, unlike proactive.

 Option 3: Reactive: Responding to events after they happen rather than anticipating them. This is essentially the opposite of proactive.

Option 4: Enthusiastic: Showing intense and eager enjoyment or interest. While it indicates energy and positivity, it does not imply taking initiative in advance.

Given that proactive is about initiating actions rather than just reacting to them, the most fitting synonym is not actually present in these options. But among the given choices, none are truly synonymous. Still, option 4 aligns somewhat with a proactive mindset in terms of approach, but not fully.

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