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: Microbiology
Sheathed microfilaria is/are -a) W. bancroftib) Loa-loac) M. perstansd) B. malayi 
Select and explain. 
A. acd, B. abd, C. abc, D. ab
D: ab
Answer: D: ab 
Explanation: Sheathed microfilaria is covered by hyaline sheath, in which larva moves backwards and forwards within the sheath, e.g. Wuchereria, Brugia and Loa loa