(三).We need flour when we bake food. But do you know that flourcan blow up casily?    On June 27, 2015, at a party in a waterpark in Taiwan, the stage suddenly caught on fire and burneddown in seconds.    People screamed and ran for their livesthrough fire that seemed to come out of nowhere.      More thanfive hundred people got hurt, and fifleen people died. A bag ofNour wuuldn'l usually burn by itself, but if you throw a lot offlour into the air and light it, the flour will explode.    When youthrow it in to the air, the surface area will become larger. Thelarger the surface area becomes, the more easily it will blow up.Other powders, like sugar, milk powders, and comstarch are justas dangerous as flour. Be careful when you use them, andremember to keep powders away from fire.
【題組】42. What does the word explode mean?
(A) hit.
(B) respect.
(C) bake. 
(D) blow up.