Task: Question Answering
Input (English): Question: A basic component of spectrophotometers is the monochromator. Its function is: 
 Options:  <1> Connect the different wavelengths from the source to achieve greater light power. <2> Transform the optical signal measured by the detector into an electrical signal. <3> Disperse the light separating the wavelengths that compose it and select a narrow band. <4> Amplify the analytical signal by improving the signal-to-noise ratio. <5> Decrease the power of the light beam to eliminate the background noise of the spectrophotometer.
Output (English): 3