In a random sample of fishes from a pond, the mean tail length was 6.0 mm and the reference tail length for the species was found to be 4.0 mm with a standard deviation of 2.0. if there are 16 fishes, what would be the z score and which hypothesis would be accepted?

Z= 4 and Ha
Z = 5 and Ho
Z= 3 and Ha
Z=2 and Ho