参考答案

正确答案：A
解析：根据What it's not部分。该部分主要澄清了哪些问题或现象不属于抑郁症的症状。该部分的第二段“Feeling down every now and then--and even being sad--are normal emotions that everyone has．Even though it might not seem very good，it's actually healthy to feel and express sadness and anger．”feeling down表示“感觉不快”，短语now and then与题目中occasional对应。