The value of $$\displaystyle\int_1^a [x]f'(x)\,dx, a > 1$$, where $$[x]$$ denotes the greatest integer not exceeding $$x$$ is

A

$$af(a) - \{f(1) + f(2) + \ldots + f([a])\}$$

B

$$[a]f(a) - \{f(1) + f(2) + \ldots + f([a])\}$$

C

$$[a]f([a]) - \{f(1) + f(2) + \ldots + f(a)\}$$

D

$$af([a]) - \{f(1) + f(2) + \ldots + f(a)\}$$