Q1. Noise can be introduced into copper, aluminum, and other wire types by ____. a. spectral interference b. hyperspectral interference c. electromagnetic interference d. optical interference Q2. ____ is the most widely used error-detection method. a. Hamming code b. SHA1 c. Cyclic redundancy checking d. Message Digest Q3. A(n) ____ is a data transmission event or group of events representing a bit or group of bits. a. signal b. modulation c. motion d. indicator Q4. Frequency modulation is also called ____. a. break-shift keying b. amplitude-shift keying