The line from "The Most Famous Woman in American" that expresses an opinion is: "You'll see what I mean. You'll love her." The last option is the correct option.
The Breakdown
This line is an expression of the speaker's opinion about the woman in question. The use of the words "you'll love her" suggests that the speaker has a positive opinion of the woman and believes that the listener will share this opinion once they meet her. The line is subjective and reflects the speaker's personal viewpoint, rather than an objective fact.
What is an Opinion?
Opinions are subjective and based on personal preferences or judgments. They can vary from person to person and are not necessarily based on objective facts. In this case, the speaker is sharing their subjective viewpoint that the listener will have a positive impression of the woman.