A nurse is preparing to administer penicillin G benzathine 1.2 million units IM now. The amount available is penicillin G benzathine 600,000 units/mL. How many mL should the nurse administer?
(Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)

Choice A Reason: This is incorrect because sickle-cell anemia is a genetic disorder that affects the shape and function of red blood cells. It does not affect the AFP level, which is a protein produced by the fetus and placenta. Sickle-cell anemia can be detected by other prenatal tests, such as hemoglobin electrophoresis or DNA analysis.

Choice B Reason: This is incorrect because cardiac defects are structural abnormalities of the heart or blood vessels that affect the blood flow and oxygen delivery to the fetus. They may cause an increased AFP level, not a decreased one, as they can lead to fetal distress or edema. Cardiac defects can be detected by other prenatal tests, such as fetal echocardiography or ultrasound.

Choice C Reason: This is correct because Down syndrome is a chromosomal disorder that results from an extra copy of chromosome 21. It causes various physical and mental developmental delays and defects in the fetus. It is associated with a decreased AFP level, as well as decreased levels of human chorionic gonadotropin (hCG) and unconjugated estriol (uE3). Down syndrome can be confirmed by other prenatal tests, such as amniocentesis or chorionic villus sampling (CVS).

Choice D Reason: This is incorrect because respiratory disorders are problems that affect the breathing and gas exchange of the fetus. They may cause an increased AFP level, not a decreased one, as they can lead to fetal distress or edema. Respiratory disorders can be detected by other prenatal tests, such as fetal biophysical profile (BPP) or nonstress test (NST).

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.