Bags of Popcorn Bottles of Soda

Bags of Popcorn Bottles of soda

-Jenny buys sodas and popcorn. Sodas sell for $1 and popcorn sells for $2 a bag. Currently she is in consumer equilibrium, with the marginal utility from her last dollar spent on popcorn equal to 100 units of utility. The marginal utility from her last dollar spent on sodas is

A) 20 units of utility.
B) 30 units of utility.
C) 50 units of utility.
D) 100 units of utility.