[amp_mcq option1=”70mm” option2=”80mm” option3=”90 mm” option4=”105 mm” correct=”option2″]
The correct answer is $\boxed{\text{B. }80\text{ mm}}$.
The normal annual precipitation at stations X, A, B and C are 700 mm, 1000 mm, 900 mm and 800 mm respectively. This means that on average, station X receives 700 mm of precipitation per year, station A receives 1000 mm of precipitation per year, station B receives 900 mm of precipitation per year, and station C receives 800 mm of precipitation per year.
If the storm precipitation at three station A, B and C were 100 mm, 90 mm and 80 mm respectively, then the storm precipitation for station X will be 80 mm. This is because the storm precipitation is the amount of precipitation that falls in a short period of time, usually less than 24 hours. It is often caused by thunderstorms or other severe weather events. The storm precipitation for station X is 80 mm because this is the amount of precipitation that fell at station X during the storm.
The other options are incorrect because they do not represent the amount of precipitation that fell at station X during the storm.