Question

modulation means...
○ to change key.
○ to change color.
○ to change address.

Explanation:

Modulation in communication technology is about altering carrier - wave properties for signal transmission, not about changing key, color, or address as presented in the options.

Answer:

None of the above options are correct. In general, modulation in communication - related fields means to change some characteristics of a carrier wave (such as amplitude, frequency, or phase) according to the information - bearing signal.