30, 34, 43, 59, 84, 120, __

Key pattern: the differences between consecutive terms are consecutive perfect squares.

1. 34 - 30 = 4 = 2^2

2. 43 - 34 = 9 = 3^2

3. 59 - 43 = 16 = 4^2

4. 84 - 59 = 25 = 5^2

5. 120 - 84 = 36 = 6^2

6. Next difference should be 7^2 = 49, so x - 120 = 49

Therefore x = 120 + 49 = 169. The correct answer is 169.