[单选题]
An ideal fluid flows at 12 m/s in a horizontal pipe. If the0zf) z(a7u4nzhwsgp* gsa g+, pipe narrows t9i;4ew c;- a( dmqu;h;l7wzsxqb64fnqn n3 ed o half its original radius, what is the flow speed in the narrower sectionn;6q7le3ni daq; xn- 4f(w;s m hbdqu; w94ezc?
