Which allele combination represents a male who has an X-linked recessive disorder?

Without the answer options I cannot tell you the answer exactly, however X linked disorders are found only on X chromosomes and are indicated by a lowercase letter next to the X. Xr would be an example of the notation. A male has one X chromosome and one Y chromosome, where females have two X chromosomes.

The allele combination of a male with an x linked recessive disorder would look something like XrY.