This is a matter of life and death the cost of one pencil is $3, and the total cost of three pencils is $9. which of the following is true? a. the number of pencils and the total cost are in a proportional relationship because the cost increases with the number of pencils. b. the number of pencils and the total cost are in a proportional relationship because the cost does not increase with the number of pencils. c. the number of pencils and the total cost are in a proportional relationship because the cost of zero pencils is $0, and each pencil costs $3. d. the number of pencils and the total cost are in a proportional relationship because the cost of zero pencils is $0 and it does not increase proportionally with the number of pencils.