A National Survey of Asthma Conducted on May 1, 2012

A national survey of asthma conducted on May 1, 2012, obtained the following results for the state of Oklahoma:
X = The number of residents with asthma
Y = The population of the state on June 30, 2012, and all members of the population were considered at risk
Z = The number of new cases of asthma diagnosed during 2012.
The incidence rate of asthma during 2012 (per 100,000) would be expressed as:

A) (X/Y) × 100,000.
B) (Z/X) × 100,000.
C) (Z/Y) × 100,000.
D) (X/Z) × 100,000.
E) None of these is correct.