Answer: A) 0
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Explanation:
The information that b < d tells us that the degree of the numerator is smaller than the degree of the denominator. The denominator outgrows the numerator. I suggest looking at a table of values (select random positive integers for a,b,c,d where b < d).
So it's effectively similar to the end behavior of y = 1/x. As x gets larger, y approaches 0. Or you could look at something like y = (x^2)/(x^3) and it's the same idea.
Because r(x) approaches 0, this means we have a horizontal asymptote at y = 0.
