The method used to obtain colored light from a filament lamp is additive. A filament lamp is a device that emits white light when it's turned on. However, the light can be made to appear colored by using a technique called additive color mixing. In this method, colored filters are used to filter the white light emitted by the filament lamp. The colored filters absorb some of the light wavelengths and allow others to pass through. When different colored filters are used, the colors of the light that passes through them combine to produce a new color. This method is called additive because the colors of light are added together to produce a new color.
The correct option is A. additive.