Correct Answer : Option (D) :   Optical transmission losses
                                                                                                                
                                                                                                                                                                        
                                                        Explanation : For anti-reflection coated optics, the optical transmission losses may be 1% or 2% at each air to glass or glass to air optical control surface within the telescope, including windows or sensor covers or surfaces. For uncoated optics, the loss per surface is about 4% to 5%.