Two number \( k_1 \) and \( k_2 \) are randomly chosen from the set of natural numbers. Then, the probability that the value of \( i^{k_1} + i^{k_2} \) \( (i = \sqrt{-1}) \) is non-zero, equals:
\( \frac{1}{2} \)
\( \frac{3}{4} \)
\( \frac{1}{4} \)
\( \frac{2}{3} \)