This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Retina, Subject name: Ophthalmology
Investigation of choice for diagnosing macular edema:- 
Select and explain. 
A. Biopsy, B. FA, C. Optical coherence tomography, D. ERG
C: Optical coherence tomography
Answer: C: Optical coherence tomography 
Explanation: Optical Coherence Tomography Non-excisional "OPTICAL BIOPSY" Uses low coherence interferometry, employs michelson interferometer 830 nm infrared light, Super luminescent diode light source. Not very specific in hazy media and myopic discs