Which of the following is NOT a geometric sequence:

W) 30, 6, \(\frac{6}{5}\ldots\)

X) \(a^{2}\), \(a^{3}b\), \(a^{4}b^{2}\ldots\)

Y) 6, 13, 20\(\ldots\)

Z) \(\frac{3}{2}\), \(\frac{3}{4}\), \(\frac{3}{8}\ldots\)
Y) 6, 13, 20\(\ldots\)