What happens next?

How to convert inches to millimeters 
Understand the relationship between inches and millimeters. 
One inch is internationally accepted as being equivalent to 25.4 millimeters. 
Written as an equation, this relationship is represented as : 1 in = 25.4 mm this official, standardized measurement has been set on international records since 1959.

OPTIONS:
 A). Literally translated a millimeter by the united states postal service, the measurement refers to the value of the unit of mass used in the unit. For example, an ounce (gram) from a kilogram lumber pulp can be considered equivalent to ½ millimetres..
 B). Both inches and millimeters are units of measurement. Inches belong to the english system of measurement, while millimeters belong to the metric system of measurement..
 C). Multiply to get the number one digit. Subtract two inches from your unit to get the x/0 split as your unit weight (between 11 per-inch)..
 D). The standard measurement used in comparative quantities sets per squared mile of an atomic meter for the length of the atomic meter. This measurement states the exact weight of 2 billion square kilometers of air..
B).