Answer: Did I dissolve the sugar before adding the final three ingredients?
Explanation:
The options include:
a. What can I add to this lemonade to try and make it taste better?
b. Should I consider using a different lemonade recipe in the future?
c. Does my mother use the same recipe to make her lemonade?
d. Did I dissolve the sugar before adding the final three ingredients?
The question that Selma can ask herself to evaluate what went wrong is "Did I dissolve the sugar before adding the final three ingredients?"
Since she tasted the lemonade and saw that it didn't taste right, she should ask if the sugar was dissolves before adding the final three ingredients. If it wasn't dissolved, this could have led to the taste that the lemonade brought.