This 25-year-old male university student gave history of multiple tick bites when he was at a camp 45 days ago. Ever since, he has episodes of high grade fever accompanied by headache, myalgias, ahralgias, nausea, and occasional vomiting. After 6-7 days, his symptoms would subside. Such episodes occurred thrice with a symptom free interval of 9-10 days. O/E, his temperature was 98degF, and his pulse 72 beats per minute. His physical examination was completely within normal limits except some mild splenomegaly and skin lesions. Wright stain of this patient's peripheral blood smear was done. What is the first oral drug of choice in the above patient: -