In the sentence, "She had been working on the project for months before the dead...

Questão de Inglês da banca AMEOSC aplicada no concurso Prefeitura de Palma Sola SC (2024). Confira a resolução completa abaixo:

In the sentence, "She had been working on the project for months before the deadline was extended," which of the following options best describes the linguistic structures used and their function within the context?