The correct answer to the previous question is "C". According to English Grammar, whenever using the Past Continuous Tense, also known as Past Progressive, we must comply with the following grammatical structure: past tense of<em> to be</em> (<em>was </em>or<em> were</em>) followed by the gerund of the main verb (e.g. <em>to sleep</em>, <em>sleeping</em>).
