What Is the Relationship Between Recombination Frequency and the Actual

What is the relationship between recombination frequency and the actual physical distance on a chromosome?

A) As physical distance increases, the recombination frequency increases in a linear fashion.
B) As physical distance increases, the recombination frequency decreases in a linear fashion.
C) As physical distance increases, the recombination frequency first increases in a linear fashion, but gradually levels off to a frequency of 0.5.
D) As physical distance increases, the recombination frequency first increases, but then decreases.