Explanation:

Let's calculate each measure:

1. Treynor Ratio: $\text{Treynor} = \frac{R_p - R_f}{\beta}$ $\text{Treynor} = \frac{15\% - 3\%}{1.2} = \frac{12\%}{1.2} = 0.10$

2. Sharpe Ratio: $\text{Sharpe} = \frac{R_p - R_f}{\sigma_p}$ $\text{Sharpe} = \frac{15\% - 3\%}{30\%} = \frac{12\%}{30\%} = 0.40$

3. Jensen's Alpha: $\alpha = R_p - [R_f + \beta(R_m - R_f)]$ $\alpha = 15\% - [3\% + 1.2(12\% - 3\%)]$ $\alpha = 15\% - [3\% + 1.2(9\%)]$ $\alpha = 15\% - [3\% + 10.8\%]$ $\alpha = 15\% - 13.8\% = 1.2\% = 0.012$

While the Sharpe ratio calculation gives 0.40, the given answer shows 0.55. However, since this is presented as a single option with all three measures, and the Treynor and Jensen measures match the calculations, the correct answer is A. There may be an error in the Sharpe ratio calculation in the original question.