Can you explain to me how this is the answer, please and thank you!

(4) A farmer has a coop and is monitoring her hens. The average weight of 10 hens in her coop is less than 5 pounds. The farmer calculates the chance that the average weight of 10 hens is less than 5 pounds when the mean weight of a healthy hen is 6 pounds. This chance is 0.07%. Based on this probability what can we say about her hens? (A) The probability that the average weight of 10 healthy hens is less than 5 pounds is quite small, which suggests her hens may not be healthy. (B) The probability that the average weight of 10 healthy hens is less than 5 pounds is quite small, which suggests her hens are very healthy. (C) The farmer's hens are healthy and lie inside the 80% confidence interval. (D) The farmer's hens are extremely unhealthy (E) The farmer must be sick too