Topic: Degree of Comparison,

Best Answer Explained in Below-:

The phrase "Easier said - done" is a common idiom that emphasizes the difference between expressing an idea and actually executing it. In its complete form, the phrase is typically stated as "Easier said than done." This indicates that while it may be simple to talk about or suggest a solution, the actual implementation is much more challenging.

Among the given options, "than" is the correct choice because it functions as a comparative conjunction, linking the two contrasting elements of the statement: the ease of saying something versus the difficulty of doing it. The word "be" (Option A) does not fit contextually, as there is no need for a verb in this structure. "And" (Option C) implies addition rather than comparison, thus failing to convey the contrast necessary for the phrase. Finally, "on" (Option D) is irrelevant in this context as it does not serve the intended meaning of comparison.

Therefore, "than" provides the necessary contrast to clarify that the act of doing is significantly more difficult than simply saying it. This makes "than" the correct answer, completing the phrase with its intended meaning.