K For the function shown below, find (if the quantity exists) (A) lim f(x), (B) lim f(x), (C) lim f(x), and (D) f(0). X -+ 0 + X-07 X-+ 0 21 - x2 for xSO f( x ) = 21 + x 2 , for x > 0 . . . (A) Select the correct choice below and fill in any answer boxes in your choice