For part of the summer of this year, Sammi worked full-time at a local accounting firm. Sammi is a 19-year-old accounting student attending a state university and does not work during the rest of the year. Over the summer, Sammi earned a total of $9,500. How many quarters of coverage has Sammi attained for Social Security purposes based only on this year's earnings? 

 a. None, since she did not work a full calendar quarter. 

b. 1 quarter, the maximum she can earn in a 3-month period. 

c. 2 quarters. 

d. 4 quarters.