These 17 are probably the beginning of an eye stye.
答案：(C) symptoms
語意「這些『症狀』可能是針眼的開始」，symptoms（症狀）符合醫療語境；incidents（事件）、measures（措施）、explanations（解釋）都不合。
前面兩句在講「眨眼會痛」「發現一個小紅點」，讀起來像在描述「發生的事」，所以你很容易挑 incidents（事件）。但 incident 指的是外部發生的事故或事件，像 a traffic incident（一起交通事故）；身體自己出現的不舒服和外觀變化，英文叫 symptom（症狀）。
先確認 These 指的是什麼。往前看兩句：a bit of pain on your eyelid（眼皮有點痛）、a tiny red spot（一個小紅點）——一個是你感覺到的不適，一個是看得到的異狀，兩個都是身體傳出來的訊號。再看空格後面：are probably the beginning of an eye stye（很可能是針眼的開始），整句是「這些症狀很可能是針眼的初期徵兆」，醫療語境非常明確。
incidents（事件、事故）指外部發生的事，不用來講身體狀況。measures（措施）是為了解決問題採取的行動，常見 take measures to prevent it（採取措施加以預防），但這裡還沒進到「怎麼處理」，處理方式要到文章最後才出現。explanations（解釋、說明）是對原因的說明，紅點和疼痛本身不是解釋。
symptom（症狀）、show symptoms of（出現……的症狀）、a common symptom（常見症狀）、incident（事件、事故）、take measures（採取措施）、explanation（解釋、說明）、be accompanied by（伴隨著）。
You begin to notice a bit of pain on your eyelid each time you blink. You 16 the mirror to find a tiny red spot on the base of your lower lashes. These 17 are probably the beginning of an eye stye. An eye stye is a small bump, resembling a pimple, that develops when an oil gland at the edge of an eyelid becomes infected by bacteria. These bacteria are found in the nose and are easily 18 to the eye when you rub your nose, then your eye. Pus will build up in the center of the stye, causing a yellowish spot. Usually a stye is accompanied by a swollen eye.
19 a stye can look unpleasant at times, it is usually harmless and doesn't cause vision problems. Most styes heal on their own within a few days. You might speed up healing time by gently pressing a warm washcloth 20 your eyelid for 10 minutes, 3 or 4 times a day. Make sure you don't squeeze or pop a stye like you would a pimple. Doing so may cause a severe eye infection.