Please help me with the following question. Please help me with the following question!!

In order to estimate the mean amount of time computer users spend on the internet each month, how many computer users must be surveyed in order to be 95% confident that your sample mean is within 13 minutes of the population mean? Assume that the standard deviation of the population of monthly time spent on the internet is 195 min. What is a major obstacle to getting a good estimate of the population mean? Use technology to find the estimated minimum required sample size. The minimum sample size required is D computer users. (Round up to the nearest whole number.) What is a major obstacle to getting a good estimate of the population mean? 0 A. It is difficult to precisely measure the amount of time spent on the internet, invalidating some data values. 0 B. There may not be 865 computer users to survey. 0 C. The data does not provide information on what the computer users did while on the internet. 0 D. There are no obstacles to getting a good esitmate of the population mean