What does the following equation mean?

Addict$\_$Coverage $=$ Addicts$($t$)//$ Addict$\_$Quit$\_$Rate

A$.$ Divide Addicts by Addict Quit Rate to calculate Addict Coverage

B$.$ Divide Addicts by Addict Quit Rate to calculate Addict Coverage but if Addict Quite Rate equals zero, make Addict Coverage zero

C$.$ Multiply Addicts by Addict Quit Rate to calculate Addict coverage

D$.$ Addict Coverage $=$ Addicts $[$Addict Quit Rate is commentary that specifies the dimension of the equation$]$