The correct answer is C
Doxycycline has been a mainstay of rosacea treatment for decades. Doxycycline exerts its anti-inflammatory effect via downregulation of inflammatory cytokines, MMPs and reactive oxygen species. It exerts a bacteriostatic effect by binding to ribosomal subunits, thereby preventing protein synthesis. Antimicrobial doses (50 mg per day or greater) should be avoided in order to prevent microbial resistance and changes in normal flora. Sub-antimicrobial doses have been shown effective as part of a combination treatment strategy for rosacea, and cross-sectional studies have shown lower rates of GI side effects and photosensitivity in patients on sub-antimicrobial regimens.