Final answer:
The correct verb form to complete the sentence is 'era'.
Step-by-step explanation:
The correct verb form to complete the sentence is era.
In this sentence, the verb form needs to match the past tense of the verb 'ser' (to be) to describe the student's previous job as a reporter and their current job as a subeditor. The correct verb form 'era' is the imperfect past tense of 'ser'.
Example: Antes fui reportera y ahora era la subeditora de este periódico.
Learn more about verb conjugation