To find the cost of the handbag after the discount of 31% is applied, we need to decrease the original price \( M \) by 31%. This means we want to find 69% of the original price (100% - 31% = 69%).
The correct calculation for the discounted price \( D \) would be:
\[ D = M \times (1 - 0.31) = M \times 0.69 \]
Thus, the correct interpretation of the given expression is:
D. D is 69% of the original price of the handbag.