Choice A is the correct answer. Check product rule.

1. Product: $a \times (1/a) = 1$.
2. Condition: Perpendicular lines must have a product of $-1$.
3. Conclusion: They are reciprocals, but not negative reciprocals. So generally No.

💡 Strategic Tip: Don't forget the negative sign! $m$ and $-1/m$ are perpendicular.

Choice B is incorrect because product is 1. Choice C is incorrect because they could be if $a$ involves complex numbers (out of scope) or specific sign errors in setup. Choice D is incorrect because undefined.