The correct answer is C: 29. Examine differences: 3−1=2, 6−3=3, 11−6=5, 18−11=7, next difference should follow the pattern of primes: 2, 3, 5, 7, 11, 13. So next difference = 11, giving X = 18 + 11 = 29.
A.26
B.27
C.29✓ Correct
D.30
Explanation
Examine differences: 3−1=2, 6−3=3, 11−6=5, 18−11=7, next difference should follow the pattern of primes: 2, 3, 5, 7, 11, 13. So next difference = 11, giving X = 18 + 11 = 29. Verify: 42 − 29 = 13 ✓ (next prime). The differences are consecutive primes 2, 3, 5, 7, 11, 13. So X = 29. Answer is (c) 29.
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