A theater company charges $10.50 per ticket for people of all age groups. If c represents the total number of children who bought tickets and a represents the total number of adults who bought tickets, which expression best represents the total money earned by the company from the sale of tickets?
Select one:
a. 10.5c + a
b. c + 10.5a
c. 10.5(c + a)
d. 21(c + a)