Let the total work be 1 units.

Eugene completes W units in 4 hours, so in 1 hour, Eugene will complete $\frac{1}{4}$ unit of work.

Similarly, Steve will complete $\frac{1}{6}$ unit of work in 1 hour.

When Eugene and Steve work together, total work done in 1 hour = $\frac{1}{4} + \frac{1}{6} = \frac{6+4}{24}$

Work done together in 1 hour = $\frac{10}{24} = \frac{5}{12}$

Now $\frac{5}{12}$ units of work is done in 1 hour.

Hours taken to complete 1 unit of work = $\frac{1}{5/12} = \frac{12}{5} = 2 \frac{2}{5}$


OA,C