If $f ( x )$ Is the Probability Density Function for the Blood Cholesterol Level

If $f ( x )$ is the probability density function for the blood cholesterol level of men over the age of 40 , where $x$ is measured in milligrams per deciliter, express as an integral the probability that the cholesterol level of such a man lies between 195 and $245 .$

A) $\int _ { 40 } ^ { 195 } f ( x ) d x$
B) $\int _ { 245 } ^ { 195 } f ( x ) d x$
C) $\int _ { 40 } ^ { 245 } f ( x ) d x$
D) $\int _ { 195 } ^ { 245 } f ( x ) d x$
E) $\int _ { 0 } ^ { 245 } f ( x ) d x$