A signal x(t) = 100 cos (24 π × 103t) is ideally sampled with a sampling period of 50 μsec and then passed through an ideal lowpass filter with a cut-off frequency of 15 kHz. Which of the following frequencies will be present at the filter output:
1
12 kHz only
2
8 kHz only
3
12 kHz and 9 kHz
4
12 kHz and 8 kHz