________, the situation could have been even worse if you did not call me.On the other handAs well asWhileIn particular

The sentence suggests a contrast or a different perspective on a situation. Therefore, the best option to fill in the blank is "On the other hand." This phrase is commonly used to introduce an opposing idea or an alternative way of looking at a situation, indicating that while there were challenges, the outcome could have been more negative without intervention.

Here's how the complete sentence reads:

"On the other hand, the situation could have been even worse if you did not call me."

This choice makes sense as it sets up a perspective that acknowledges a difficult situation but also points out a mitigating factor. The other options do not fit as appropriately, as "As well as" suggests addition, "While" introduces a contrast but does not fit smoothly, and "In particular" does not relate to the overall context of the statement.