A block of mass 40 kg slides over a surface, when a mass of 4 kg is suspended through an inextensible massless string passing over frictionless pulley as shown below. The coefficient of kinetic friction between the surface and block is 0.02. The acceleration of block is: (Given $$g = 10$$ m s$$^{-2}$$.)

A

$$\frac{8}{11}$$ m s$$^{-2}$$

B

1 m s$$^{-2}$$

C

$$\frac{1}{5}$$ m s$$^{-2}$$

D

$$\frac{4}{5}$$ m s$$^{-2}$$