Answer:
3rd option
Explanation:
A porportional relationship can be described by
where x is the number of days, y is the amounts of food and k is the constant rate. (for this instance)
Looking at Classrom B, the amounts of food and cinstant rate isn't porpotional. Soxthat eliminates B and D.
For the 3rd option, the food amount is porportional as x increases. The unit rate here is 1,9 so the correct option is the 3rd option.