Fresh graduate applying for multiple positions advertised by a recruitment company?

I am a fresh accounting graduate and I want to keep my options open. I saw an ad advertised by a recruitment company, demanding for a long list of accounting range jobs and i was attracted to the following : accounts payable executive, accounts receivable executive and accounts executive. Do i write different cover letters to apply for all 3 jobs of just squeeze everything into 1 cover letter? I dont want to give the impression that I am spamming or uncertain of what i wanna do, you see! And since its a recruitment company, who do i address it to? Dear Recruiter??