In order to get the amount she earns in a year, you have to multiply the number of weeks in the year by the amount she earns each week. The year has approximately 52 weeks, and calling x the amount Rita earns each week; therefore, 52 times x, represents the amount she earns in a year.
If x is what Rita makes in a week and we want to find out what Rita make's in a year. First there are 52 weeks in a year so all we would have to do is multiply 52 times x or 52x. So your answer is answer choice C. 52x. Hope this helped. :)