A can do a certain work in 15 days. B is 25% more efficient than A. Both worked together for 4 days. C alone completed the remaining work in 8 days. A, B and C together will complete the same work in ?

A

$$4\frac{1}{2}$$ days

B

$$5$$ days

C

$$6\frac{1}{2}$$ days

D

$$4$$ days