Step 1: Understand the concept of the Profit Margin Ratio. It is a financial metric used to evaluate a company's profitability by comparing its net income to its net sales. This ratio indicates how much profit is generated for every dollar of sales.
Step 2: Analyze the given formulas and identify the components involved. The Profit Margin Ratio specifically uses 'Net Income' and 'Net Sales' in its calculation, as it measures profitability relative to sales revenue.
Step 3: Recall the correct formula for the Profit Margin Ratio: \( \text{Profit Margin Ratio} = \frac{\text{Net Income}}{\text{Net Sales}} \). This formula aligns with the definition of the ratio, focusing on net income as the profit and net sales as the revenue base.
Step 4: Eliminate incorrect options by comparing their components to the definition of the Profit Margin Ratio. For example, \( \frac{\text{Net Sales}}{\text{Net Income}} \) reverses the intended relationship, \( \frac{\text{Gross Profit}}{\text{Total Assets}} \) measures a different concept, and \( \frac{\text{Operating Expenses}}{\text{Net Sales}} \) does not relate to profitability.
Step 5: Confirm that the correct formula is \( \text{Profit Margin Ratio} = \frac{\text{Net Income}}{\text{Net Sales}} \), as it accurately represents the relationship between profit and sales revenue.