A client is diagnosed with a herpes infection. Which drug is considered the first-line treatment?

A. Penicillin: Penicillin is effective against bacterial infections such as syphilis and streptococcal infections, but it has no activity against viral infections like herpes simplex virus. B. Tetracycline: Tetracyclines are broad-spectrum antibiotics used to treat bacterial infections, including acne and certain sexually transmitted infections, but they are not effective for viral infections such as herpes. C. Ceftriaxone: Ceftriaxone is a cephalosporin antibiotic used to treat bacterial infections including gonorrhea. It has no effect on viral replication and cannot treat herpes infections. D. Acyclovir: Acyclovir is an antiviral medication that inhibits herpes simplex virus replication. It is the first-line treatment for both initial and recurrent herpes infections, reducing severity, duration, and frequency of outbreaks.