What was one of the main purposes of the first computer systems?
a. performing financial transactions
b. sending personal communications (i. e., e-mail)
c. documenting patient medical information
d. creating media presentations for meetings?

Financial transactions were one of the first purposes of computers. This is where "ticker tapes" came from; early computers were used to keep track of how stocks were performing. Computers in early days used large mainframe systems and punch cards to keep track of this type of data.

Social networking sites d. online forumsthe first recognizable social media site,  six  degrees, was created in 1997. it enabled users to upload a profile and make friends with other users. in 1999, the first blogging sites became popular, creating a social media sensation that's still popular today.