The largest prime factor of (2 ⁴ )² -1 is -

A 3

B 5

C 17

D 19

Correct Answer: Option C

(2 ⁴ )² -1
=(2 ⁴ )² -(1)²
=(2 ⁴+1)(2 ⁴-1) [a²-b²=(a+b)(a-b)]
=(16+1)(16-1)
=17×15
=17×5×3
বৃহত্তম মৌলিক সংখ্যা 17