2. In an acute triangle $\triangle ABC$, two altitudes $BY'$ and $CC'$ intersect at $H$. If $AH + AB' + AC' = BC + BB' + CC'$, then $\angle BAC = (\quad)$.
(A) $75^{\circ}$
(B) $60^{\circ}$.
(C) $45^{\circ}$
(D) $30^{\circ}$