This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
Following is the etiological agent of Rocky Mountain spotted fever: 
Select and explain. 
A. R. rickettsia, B. Rochalimae quintana, C. R. tsutsugamushi, D. Coxiella burnetti
A: R. rickettsia
Answer: A: R. rickettsia 
Explanation: Ans. is 'a' i.e., R. rickettsiaRef: Harrison, 19th/e, p. 1154; Ananthanarayan, 9th/e, p. 405)Rocky Mountain spotted fever is a bacterial infection transmitted by a tick. Serious damage to organs such as your kidneys and heart. Severe headache, high fever are important findings. A few days later, a rash usually appears on the wrists and ankles.