In the local community centers carpentry club, 3 children can build a model of a boat in 10 days. Working together, 5 adults can build the same model in 3 days. At the same rate, if 2 children and 2 adults work together ideally, how many days will it take them to build the boat model?

a. 4

b. 5

c. 6

d. 7

e. 12

f. 14

g. 24