In 1972, one could buy a bag of chips, a pound of hamburger, a package of buns,

Question:

In 1972, one could buy a bag of chips, a pound of hamburger, a package of buns, and a small bag of charcoal for about $2.50. If the same goods today cost $6.00, then which pair of CPIs would make the cost in today's dollars the same for both years?
a. 60 in 1972 and 150 today
b. 65 in 1972 and 156 today
c. 75 in 1972 and 160 today
d. 90 in 1972 and 145.8 today