This question assesses the ability to find a synonym that best fits the context. The correct answer is A. 'understand' is the closest synonym to 'figure out' in this context, meaning to comprehend or to come to know. Option B, 'guess', implies a lack of certainty, which is not suitable here. Option C, 'assume', means to take for granted without proof, which is not the intended meaning. Option D, 'realize', can mean to understand fully, but it is less precise than 'understand' in this context. The focus is on finding a synonym that matches the meaning of 'figure out' in the given sentence.