Question Analysis:
We are given that 20 men can complete a piece of work in 42 days, working 8 hours per day. We need to find the number of men required to complete the same work in 33 days, working 5 hours per day.

Let's solve this problem step by step.

Step 1: Calculate the total work
We know that the amount of work is constant. Therefore, the total work done by 20 men in 42 days, working 8 hours per day can be calculated as follows:
Total work = (Number of men) × (Number of days) × (Number of hours per day)

Step 2: Calculate the work done by each man per day
Since 20 men are working for 42 days, the work done by each man per day can be calculated as follows:
Work done by each man per day = Total work / (Number of men) / (Number of days)

Step 3: Calculate the number of men required
Now, we need to find the number of men required to complete the work in 33 days, working 5 hours per day. Let's assume the required number of men is "x". We can set up the following equation:
Total work = (Number of men) × (Number of days) × (Number of hours per day)

Step 4: Solve the equation to find the value of x
Substituting the given values into the equation, we get:
Total work = x × 33 × 5

Step 5: Calculate the number of men required
Now, we can solve the equation to find the value of x:
x = Total work / (Number of days) / (Number of hours per day)
x = Total work / (33 × 5)

Calculations:
Let's calculate the total work done by 20 men in 42 days, working 8 hours per day:
Total work = 20 × 42 × 8 = 6720

Now, let's calculate the work done by each man per day:
Work done by each man per day = 6720 / 20 / 42 ≈ 8

Finally, let's calculate the number of men required to complete the work in 33 days, working 5 hours per day:
x = 6720 / (33 × 5) ≈ 41

Therefore, the correct answer is option D) 41.