"For 1-year SPX options, we observe that the 25-delta put implied volatility is at 45%, the 50-delta call implied volatility is at 30%, the 25-delta call implied volatility is at 35%. These observations suggest that the option-implied SPX 1-year return risk-neutral distribution is

(a) normally distributed, (b) positively skewed, (c) thin tailed, (d) negatively skewed"