4. A rectangle intersects with a circle as shown in the figure, $\mathrm{AB}=4$, $\mathrm{BC}=5, \mathrm{DE}=3$, then $\mathrm{EF}$ equals
(A) 6 ; (B) 7 ;
(C) $\frac{20}{3}$; (D) 8 ;
(E) 9 .
B

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