Which diagram represents the directions of the velocity, V, and accelerations, a, of a toy car as it moves in a clockwise, horizontal, circular path at a constant speed?

Ascientist notices that an oil slick floating on water when viewed from above has many different colors reflecting off the surface, making it look rainbow-like (an effect known as iridescence). she aims a spectrometer at a particular spot and measures the wavelength to be 750 nm (in air). the index of refraction of water is 1.3