Single select row count

I have 2 single select . 1st is Household name & 2ed is member’s name details The value of 2ed select will be changes depends on 1st select. How will i get the row count of 2ed select

(new[]{1,7,9,23,200,-997}).Count(x=> F(x))

where 1,7,9, etc are your options from the second select and the F(x) is the filtering function you apply to the second question based on the value of the first one.