Nellie is buying bird seed to put in her bird feeders. She uses about 10 pounds of bird seed each week, but has room to store any extra that she purchases. The bird seed comes in 3 different sizes as given below:3.5 pounds for $2.527.5 pounds for $5.4011 pounds for $7.92Nellie is trying to be a smart shopper and get the best deal on the bird seed. Which size bag of bird seed should Nellie buy?a. Nellie should buy the 3.5 pound bags because they have the cheapest unit price b. Nellie should buy the 7.5 pound bags because they have the cheapest unit price c. Nellie should buy the 11 pound bags because they have the cheapest unit price. d. Nellie should buy any size she wishes because they all have the same unit price.