To determine which statement is true regarding horizontal asymptotes, let's analyze each option:
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A horizontal asymptote cannot be crossed: This statement is false. It is possible for a function to cross its horizontal asymptote; horizontal asymptotes describe the behavior of the function as it approaches infinity or negative infinity, but the function can cross this line in finite intervals.
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Exponential functions don't always have a horizontal asymptote: This statement is true. While some exponential functions have a horizontal asymptote (e.g., \(y = e^{-x}\) approaches \(y = 0\) as \(x \to \infty\)), others (e.g., \(y = e^{x}\)) do not have a horizontal asymptote as they grow without bound.
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Two of these are correct: Since we've established that only the second statement is true, this option is false.
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None of these are correct: This option is also false because the second statement is indeed correct.
Therefore, the correct answer is that Exponential functions don't always have a horizontal asymptote.