A 60 kg body is pushed horizontally with just enough force to start it moving across a floor and the same force continues to act afterwards. The coefficient of static friction and sliding friction are $0.5$ and $0.4$ respectively. The acceleration of the body is :
(A) $6 \mathrm{~m} / \mathrm{s}^{2}$
(B) $4.9 \mathrm{~m} / \mathrm{s}^{2}$
(C) $3.92 \mathrm{~m} / \mathrm{s}^{2}$
(D) $1 \mathrm{~m} / \mathrm{s}^{2}$