The answer would be D.
The reason behind this is, because what you really need to do is to just add the denominators. However, in this case, we need a common denominator. The common denominator would be 10, because 2 and 5 are factors of 10. Knowing this, we have to convert the fractions into the common denominator, which would be 4/10, 6/10, and 5/10. The first fraction we get from doing 2/5 multiplied by 2. The second fraction we get from doing 3/5 multiplied by 2. The third fraction we get from doing 1/2 multiplied by 5. Neatly, we have to add the fractions up giving us, 15/10, which can be converted into 1 1/2. Finally, we just have to add all the wholes up and 1 1/2, 2 + 3 + 4 + 1 1/2, getting us a total of 10 1/2 hours.
Hopefully this helped!