What is the best transformation for "She has a good understanding of French" using "understand"?

The best transformation of the sentence "She has a good understanding of French" using "understand" is accurately captured in the option that states "She is able to understand French well." This transformation effectively conveys the original meaning, emphasizing her capability and proficiency in the French language.

This option highlights that she possesses the ability to understand French, which aligns closely with the idea of having a good understanding. It suggests a strong level of competence without losing the essence of the original statement.

The other transformations vary in their implications and may not maintain the same level of nuance. For instance, some may imply a lesser degree of ability or proficiency, which deviates from the original intent of conveying a robust understanding. Therefore, the chosen answer preserves both the meaning and intent of the original phrase while utilizing the required verb form "understand."