Correct Option (B)
The given sequence is 4, 196, 16, 144, 36, 100, 64, X. This sequence can be analyzed as two alternating sub-series:
- Sub-series 1 (Terms at odd positions: 1st, 3rd, 5th, 7th): 4, 16, 36, 64.
- These terms are the squares of consecutive even numbers:
- 4 = 2²
- 16 = 4²
- 36 = 6²
- 64 = 8²
- Sub-series 2 (Terms at even positions: 2nd, 4th, 6th, 8th): 196, 144, 100, X.
- These terms are the squares of decreasing even numbers:
- 196 = 14²
- 144 = 12²
- 100 = 10²
- Following this established pattern, the next term in Sub-series 2 would be the square of 8.
- Therefore, X = 8² = 64.
Incorrect Options:
Options A (48), C (125), and D (256) are incorrect as they do not adhere to the identified numerical patterns of either sub-series within the given sequence. 48 is not a perfect square fitting the pattern. 125 is 5³, not a square in the sequence. 256 is 16², which does not follow the decreasing even number square progression (14², 12², 10², 8²) required for the position of X.