17・131 In $\triangle A B C$, $A B=12, A C=7, B C=10$. If the lengths of sides $A B$ and $A C$ are each doubled, while the length of $B C$ remains unchanged, then, $\triangle A B C$ will have
(A) the area doubled.
(B) the height doubled.
(C) the area quadrupled.
(D) the median unchanged.
(E) the area become 0.
(1st American High School Mathematics Examination, 1950)