For 2016, Roberta is a self-employed truck driver with earnings of $45,000 from her business. During the year, Roberta received $2,500 in interest income and dividends of $500. She also sold investment property and recognized a $1,500 gain. What is the amount of Roberta’s self-employment tax (Social Security and Medicare taxes) liability for 2016?

a. $2,790
b. $3,443
c. $6,358
d. $6,885
e. $7,115