This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Which of the following statement is true regarding Acanthamoeba keratitis? 
Select and explain. 
A. For the isolation of the causative agent, corneal scraping should be cultured on a nutrient agar plate, B. The causative agent, Acanthamoeba is a helminth whose normal habitat is soil, C. Keratitis due to Acanthamoeba is not seen in the immunocompromised host, D. Acanthamoeba does not depend upon a human host for the completion of its life-cycle
D: Acanthamoeba does not depend upon a human host for the completion of its life-cycle
Answer: D: Acanthamoeba does not depend upon a human host for the completion of its life-cycle 
Explanation: For the isolation of causative agent, corneal scraping should be cultured on non-nutrient agar (not nutrient agar). 'Culture on non-nutrient agar (E. coli enriched) may show trophozoites within 48 hrs : which gradually turn into yeasts. - khurana
Normal habitat is soil, water and dust but it is an amoeba (not a helminth)
Keratitis due to Acanthamoeba may be seen both in immunocompetent and immunocompromised hosts.
In contrast to many another pathogenic amoeba, this organism is not naturally parasitic and does not require a host.