Which of the following individuals are required to file a tax return for 2018? Should any of these individuals file a return even if filing is not required? why or why not?

a) Patricia, age 19, is self-employed single individual with gross income of $5,200 from an unincorporated business. Business expenses amounted to $4,900.

b) Mike is single and is 67 years old. His gross income from wages was $10,800.

c) Ronald is dependent child under age 19 who received $6,800 in wages from a part-time job

d) Sam is married and files a joint return with his spouse, Lana. Both Sam and Lana are 67 years old. Their combined gross income was $24,250.

e) Quinn, age 20, is a full-time college student who is claimed as a dependent by his parents. For 2018, Quinn has taxable interest and dividends of $2,500