Fill in the blank (_) in the following sentence from the following choices.
Sentence: Mary made a fancy cheesecake to celebrate Rebecca's birthday, but _ messed up the recipe.

Choice 1: Mary made a fancy cheesecake to celebrate Rebecca's birthday, but Mary messed up the recipe.
Choice 2: Mary made a fancy cheesecake to celebrate Rebecca's birthday, but Rebecca messed up the recipe.
Which of the choices is correct? Respond with only "1" or "2" and no additional text.
1
2. However, it's important to note that the sentence implies that Mary made the mistake, but the sentence structure allows for the possibility of