**Which of the following statements is true about the t-distribution?**

**a**. For small sample sizes, the t-distribution has the same properties as the normal curve.

**b**. For large sample sizes, the t-distribution has the same properties as the normal curve.

**c**. Like the Normal distribution, the t-distribution is symmetric for small n.

**d**. Since population standard deviation is usually unknown, the standard error uses the sample standard deviation to estimate population standard deviation.

**The Correct Answer** **is: D**