The correct answer is C (5.8%). The total return of an index includes both the price appreciation (change in the index value) and the income (dividends or interest) over the period, expressed as a percentage of the beginning value. The calculation is as follows:

$\text{Total Return} = \frac{(\text{Ending Value} - \text{Beginning Value} + \text{Income})}{\text{Beginning Value}}$

Substituting the given values:

$\text{Total Return} = \frac{(1,575 - 1,540 + 55)}{1,540} = \frac{90}{1,540} \approx 5.8\%$

Option A (1.3%) is incorrect because it reverses the beginning and ending values in the calculation. Option B (2.2%) is incorrect because it omits the income from the calculation.