This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
The standard normal distribution : 
Select and explain. 
A. Is skewed to the left, B. Has mean=1.0, C. Has standard detion=0.0, D. Has variance=1.0
D: Has variance=1.0
Answer: D: Has variance=1.0 
Explanation: The standard detion in a standard normal curve is 1.0. The variance (SD2) is thus also one. Ref: Park's Textbook Of Preventive And Social Medicine By K. Park, 19th Edition, Page 702; Park's Textbook Of Preventive And Social Medicine By K. Park, 18th Edition, Page 647; Methods in Biostatistics: For Medical Students and Research Workers By BK Mahajan, 6th Edition, Page 68