This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: parasitology, Subject name: Microbiology
The number of pairs of flagella in the below organism is 
Select and explain. 
A. 1, B. 2, C. 3, D. 4
D: 4
Answer: D: 4 
Explanation: Trophozoite of Giardia lamblia:*Shape: viewed flat-tennis or badminton racket; viewed side- pear shaped*Dorsal surface: convex*Ventral surface: concave with sucking disc*Anterior end: broad and rounded*Posterior end: tapers to a sharp point*Bilaterally symmetrical and there are 2 axostyles, 2 nuclei and 4 pairs of flagellaRef: K.D Chatterjee 13th edition, p47-48