Which of A–D are the correct validity conditions for a one-sample t-test? 

A. You should have at least 10 success and at least 10 failures in your sample.

B. You should have at least 10 success and at least 10 failures in your sample or a sample size consisting of at least 20 observations. 

C. The quantitative variable should have a symmetric distribution, or you should have at least 20 observations and the sample distribution should not be strongly skewed. 

D. The quantitative variable should have a symmetric distribution, or you should have at least 20 observations for any other shape of the sample distribution.