A team is optimizing a prompt for a text classification task. They are considering two different methods for evaluating which of their candidate prompts is best:

• Method A: For a given text input and its correct label, they measure the model's calculated probability of generating that specific correct label. A higher probability is considered indicative of a better prompt.
• Method B: They use the prompt to generate a label for a large set of text inputs. They then calculate the overall accuracy by comparing the model-generated labels to the known correct labels. A higher accuracy score is considered indicative of a better prompt.

Analyze the primary advantages and disadvantages of using Method A compared to Method B for evaluating prompt effectiveness in this scenario.