In most public health and related research, what does the 95% refer to in the phrase "95% confidence interval" (for a population level quantity, such as a population mean, mean difference, relative risk etc..)?

a. A 95% chance that the study results are correct.

b. A 95% chance the null hypothesis in not true.

c. For 95% of studies that are based on a random sample(s) from a population(s), the 95% percent confidence interval will contain the true value of the population level quantity,

d. For 95% of studies that are based on a random sample(s) from a population(s), the 95% percent confidence interval will contain the value of study based estimate (sample mean difference, sample relative risk etc..) of the population level quantity.