Step 1: Standard relation between mean, median, and mode.
The relationship between mean (\( M \)), median (\( Md \)), and mode (\( Mo \)) for a skewed distribution is given by the empirical formula:
\[
M = \frac{Mo + 2Md}{3}
\]
Step 2: Manipulating the formula.
Rearranging the formula to express the mean in terms of median and mode:
\[
M = \frac{Mo + 2Md}{3}
\]
Multiplying through by 3:
\[
3M = Mo + 2Md
\]
Now, subtract \( 2Md \) from both sides:
\[
3M - 2Md = Mo
\]
This simplifies to:
\[
Mo = 3M - 2Md
\]
Step 3: Conclusion.
Therefore, the correct relation is \( Mo = 3M - 2Md \), which corresponds to option (D).