Context: BPA always does its research prior to accepting media invitations.
Possibility 1): Yesterday, BPA received an invitation from Sky News. After investigating the background of the media organization,the reporter, and the subject of the interview, BPA will decide whether to accept or reject the invitation.
The use of "the" means there is only one of each, and that they are specific to a discussion or context that is already known, earlier in the text or content.
Possibility 2) As a general rule: After investigating the background of a media organization, reporter, and the subject of an interview, BPA decides whether to accept or reject an invitation.
The lack of "the" would only make sense in a general statement.
Possiblity 3) As a general rule, after investigating the background of media organizations, reporters, and subjects of interviews, BPA decides whether to accept or reject invitations.
General statements can also be in the plural.