Fill in the blank with the correct option.

The candidate assured the interviewers that the dip in her grades during her second semester was an ________ since she had always been a top scorer in the first semester.

anomaly

The correct answer is Option (1) - anomaly

The candidate assured the interviewers that the dip in her grades during her second semester was an __anomaly______ since she had always been a top scorer in the first semester.

Here's why:

Anomaly : means something unusual or different from the pattern. In this context, the candidate's lower grades in the second semester are unusual compared to her history of being a top scorer.
Allay :  means to lessen or soothe. It doesn't fit because the candidate isn't trying to calm the interviewers, but explain the lower grades.
Adage : is a wise saying or proverb. It doesn't make sense in the context of explaining grades.
Abatement: means a reduction or lessening. While this could be related to the grades, "anomaly" is a more specific term that emphasizes the unusual nature of the dip in grades.

Therefore, "anomaly" is the most appropriate word to fill the blank.