Select the correct statements) regarding guided mediums

a. coaxial cables are always in a balanced configuration

b. fiber optic cables require that the refractive indices of the core and cladding be the same

c. When multiple unshielded twisted pair cables are used to send data in parallel, the transmitted signal is susceptible to delay skew

d. all statements are correct

2. Select the correct statements) regarding Pulse Code Modulation (PCM).

a. PCM describes the method for converting analog signals into digital data

b. quantization noise is always experienced in the analog-to-digital conversion (ADC) process

c. failure to follow the Nyquist sampling theorem results in signal aliasing

d. all statements are correct