Study the given pattern carefully and select the number that can replace the question mark (?) in it.

Logic: The number at the end of each line is the square of the number located at the other end of the line.

(3)$$^2$$ = 9; (9)$$^2$$ = 81; (4)$$^2$$ = 16

Similarly, follow the same pattern for 5: (5)$$^2$$ = 25

So, the missing number is 25.

Thus, the correct answer is (b).