Answer:
B. The t-distribution has less spread as the degrees of freedom increase because, as n increases, s becomes closer to sigma by the law of large numbers.
Explanation:
The sample standard deviation, s gets considerably closer to the population standard deviation, σ, this trend follows the proposition of the law of large numbers whereby the mean or average value changes as the sample size, n increases. According to the law of large numbers, as the sample size increases, the sample mean gets continously closer to the population mean, sample standard deviation follows this same trend and thus variability or spread decreases as sample size increases.