Agree B should be the answer

1) (y^3 / y)^N = y^2N

Let's pick numbers. When y is smallest at 1, then N could be = 2. In this case 1^2(2) = 1 and 1 is thus < 1000

However, if we say y = 10, then N could be equal to 11. In this case 10^2(11) which is more than 1000. 1 is inconclusive

2) (5y / y)^N = 5^N

When y is at its smallest and say y=1 then N could be equal to 6. In this case, 5^6 is larger than 1000 and it would be the case with just any given value for y. Sufficient

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Best Regards,

Paul