Which of the following would be an appropriate null hypothesis?

A) The population proportion is equal to 0.60.
B) The sample proportion is equal to 0.60.
C) The population proportion is not equal to 0.60.
D) The population proportion is greater than 0.60.
E) All of these.

The null hypothesis should always be stated in terms of the population parameter, which in this case is the population proportion. Option A correctly states that the population proportion is equal to a specific value (0.60), making it an appropriate null hypothesis. Options B and C are incorrect because they refer to the sample proportion instead of the population proportion. Option D is incorrect because it specifies a one-tailed alternative hypothesis.