Read the text and answer the question.
My best friend, Emily, is the most reliable person I know. She always keeps her promises and never shares my secrets with anyone. Last week, I was feeling very anxious about the math exam. She noticed it and spent two hours video calling me to explain the difficult topics. Thanks to her, I got a high score. I'm so lucky to have such a _______________ friend.
Which adjective best fits the blank in the text?
A) supportive