The environmental scientists are those that dig deeper into the happenings on land, the sea, and the atmosphere. From the given choices, the most likely happening that will be studied by the environmental scientist is the "effect of oil spills on marine animals'. The answer is letter A.
Electromagnetic waves all travel at the speed of light when in vacuum, and essentially this same speed in normal air. Since wave speed is product of frequency and wavelength, c = f λ and λ = c/f = (3.00 x 108 m/s) / (7.5 x 1014 Hz) = 4.00 x 10-7 m = 400 x 10-9 m = 400 nm.
