Given above are the real parts of the signals I to IV. Which of the following statements are correct?
(i): Signal III is the result of the discrete Fourier transform of signal I. The associated imaginary part is 0.
(ii): Signal III is the frequency spectrum of an oscillation with a frequency.
(iii): Signal IV is the frequency spectrum of an oscillation with 2 different frequencies.
(iv): Signal IV is the result of the discrete Fourier transform of Signal III. The associated imaginary part is 0.