A man and a woman, who do not show any apparent signs of a certain inherited disease, have seven children (2 daughters and 5 sons). Three of the sons suffer from the given disease but none of the daughters are affected. Which of the following mode of inheritance do you suggest for this disease?

The mode of inheritance that is suggested for this disease is sex-linked recessive. This is because the disease is only expressed in the sons, and not in the daughters. So, the correct answer is option D. Notice that the other options are not correct. Autosomal dominant inheritance would result in the disease being expressed in both sons and daughters, sex-linked dominant inheritance would result in the disease being expressed in both sons and daughters, but with a higher frequency in daughters, and sex-limited recessive inheritance would result in the disease being expressed only in one sex, but not necessarily only in sons.