Compare the shapes of the z- and t-distributions. Question content area bottom Part 1 Choose the correct answer below. A. The distributions are both symmetric with mean 0. However, because the t-distribution uses the sample standard deviation s instead of the population standard deviation sigma, the t-distribution is uniformly StartFraction 1 Over 6 s EndFraction in the interval (minus3s,3s) and 0 elsewhere. B. The distributions are both mound shaped and symmetric. However, because the t-distribution uses the sample standard deviation s instead of the population standard deviation sigma, both the mean and variability are greater for the t-distribution than for the z-distribution. C. The distributions are both mound shaped, symmetric, and have mean 0. However, the t-distribution is more variable than the z-distribution because the t-distribution is dependent on one more random quantity, s, than the z-distribution. D. The distributions are identical. The t-distribution is a restatement of the z-distribution when the exact population standard deviation sigma is unknown