A can do a work in 4 days, B can do same work in 8 days, then the time taken by A and B to do the same work together is:

8/3 days

The correct answer is Option (1) → 8/3 days

A’s one-day work = $\frac{1}{4}$
B’s one-day work = $\frac{1}{8}$

Together, one-day work =

$\frac{1}{4} + \frac{1}{8} = \frac{2 + 1}{8} = \frac{3}{8}$

Time taken together =

$\frac{1}{\frac{3}{8}} = \frac{8}{3} \text{ days}$