Explanation:

- She is educated than her sister.

The sentence has a comparison but is missing a key word to show the degree of comparison.

- Option 1: far educated

This option is incorrect because "far" is not appropriately used to show comparison in this context. "Far more educated" would be the correct comparative form if "far" were to be used.

- Option 2: more educated

This is the correct choice. "More educated" properly uses the comparative form to show that she has a higher level of education than her sister.

- Option 3: best educated

This is incorrect. "Best" is used for superlative comparison, which compares more than two entities, not just one to another.

- Option 4: good educated

This is incorrect. "Good" is an adjective, and the correct comparative form should be "better educated" or "more educated."