Answer: d. Do not reject the null hypothesis when it is actually false.
Explanation:
A Type II error occurs when we do not reject the null hypothesis when the alternative hypothesis is actually the true statement.
i.e. actually null hypothesis was false but get not rejection.
It is also known as Beta error.
Therefore , the correct answer is A Type II error occurs when we Do not reject the null hypothesis when it is actually false .
Hence, the correct answer : d. Do not reject the null hypothesis when it is actually false