Related Questions
Correct Answer is C
Explanation
Choice A Reason: This is incorrect because it adds 10 months and 7 days to the last menstrual period, which is not Nägele's rule.
Choice B Reason: This is incorrect because it adds 9 months and 7 days to the last menstrual period, which is not Nägele's rule.
Choice C Reason: This is correct because it follows Nägele's rule, which is to subtract 3 months and add 7 days to the last menstrual period.
Choice D Reason: This is incorrect because it subtracts 4 months and adds 7 days to the last menstrual period, which is not Nägele's rule.
Choice E Reason: This is incorrect because it subtracts 4 months and adds 17 days to the last menstrual period, which is not Nägele's rule.

Correct Answer is C
Explanation
Choice A Reason: This is incorrect because sickle-cell anemia is a genetic disorder that affects the shape and function of the red blood cells. It is not related to the AFP level, which is a protein produced by the fetal liver and yolk sac.
Choice B Reason: This is incorrect because cardiac defects are abnormalities in the structure or function of the heart. They are not related to the AFP level, which is a marker of neural tube defects and abdominal wall defects.
Choice C Reason: This is correct because Down syndrome is a chromosomal disorder that results from an extra copy of chromosome 21. It is associated with a decreased AFP level, as well as increased levels of human chorionic gonadotropin (hCG) and unconjugated estriol (uE3).
Choice D Reason: This is incorrect because respiratory disorders are problems that affect the lungs and breathing. They are not related to the AFP level, which reflects the fetal development and integrity.
