Laser is the short form of Light Amplification by Stimulated Emission of Radiation. Laser beam is intense, monochromatic (that is of the single wavelength) collimated and highly coherent. The rays are completely coherent can be verified by Youngs interference experiment. If the Youngs double slit experiment is illaminated with laser light, an interference pattern is seen, but the width of the fringes is very small. Hence, option (d) is true.