Brianna, who is a senior in high school, worked at CJs coffee shop in January and February 2018, and earned $3,000. She was then unemployed until December, when she was hired as a seasonal employee at JPs department store. She earned $2,000 during December. How many quarters of coverage has Brianna earned for Social Security in 2018?

a. 1

b. 2

c. 3

d. 4