What missing code should be added to this class to ensure that calling sum$\_$of$\_$even$(\{1,2,3,4\})$ returns $6?$

class TEST

feature

sum$\_$of$\_$even$($arr: ARRAY$[$INTEGER$])$: INTEGER

local

sum: INTEGER

i: INTEGER

do

sum :$=0$

from

i :$=1$

until

i $>$ arr.count

loop

if $\_\_\_\_$ then

sum :$=$ sum $+$ arr.item$($i$)$

end

i :$=$ i $+1$

end

Result :$=$ sum

end

end

Question $8$Answer

a$.$

arr.item$($i$)\backslash \backslash 2=0$

b$.$

arr.item$($i$)$ mod $2!=1$

c$.$

arr.item$($i$)\%2==0$

d$.$

arr.item$($i$)$ mod $2=0$