A car manufacturer advertises that its new ultra-green car obtains on average 100 miles per gallon (mpg). A consumer advocacy group tested a sample of 20 cars. Each car was driven the same distance in similar conditions, and the following results on mpg were recorded.

113, 102, 97, 78, 90, 97, 117, 98, 111, 89, 90, 93, 83, 82, 96, 94, 79, 96, 101, 92

Using Descriptive Statistics of Data Analysis of Excel with a 95% confidence level, the following incomplete output is available:

Mean	95
Standard Deviation	10.58
Sample Variance	111.87
Count	20
Confidence Level (95.0%)	4.95

The margin of error of the 95% confidence interval for the mean mpg of all new ultra-green cars is

	a.	3.65
	b.	10.58
	c.	4.95
	d.	0.50