Which is true about a grating with a given slit separation, illuminated by a given beam of light? Decreasing the number of slits increases the half-width of the lines, increasing the overlap of the lines. Decreasing the number of slits increases the half-width of the lines, decreasing the overlap of the lines. Decreasing the number of slits decreases the half-width of the lines, increasing the overlap of the lines. Decreasing the number of slits decreases the half-width of the lines, decreasing the overlap of the lines.