The value of `int_1^a[x]f^(prime)(x)dxf^(prime)(x)dx `,where `a >1`, and `[x]` denotes the greatest integer not exceeding x, is (A) `af(a)-{f(1)f(2)+.....+f([a])}` (B) `[a]f(a)-{f(1)+f(2)+......+f([a])}` (C) `[a]f(a)-{f(1)+f(2)+.......+fA}` (D) `af([a])-{f(1)+f(2)+......+fA}`