Answer:
<u>Before, during and since</u>
Explanation:
Transitional words or phrases are those that help us connect ideas, sentences, and paragraphs in pieces of writing and speeches so that the ideas flow smoothly. From all the choices,<u><em> before, during</em></u> and <u><em>sinc</em></u>e are the only transitional words of time, because only they can help indicate when something happened, happens or will happen. Here are some examples of sentences using those words:
<u><em>During</em></u><em> the evenings, my father used to read the newspaper silently while having a cup of bitter coffee.</em>
<em>I haven't talked to her </em><u><em>since</em></u><em> she left to Montevideo.</em>
<em>Please, </em><u><em>before</em></u><em> you do anything, start doing your homework. It's already late.</em>