Given below is a pedigree chart showing the inheritance of a certain sex-linked trait in humans.

The trait traced in the above pedigree chart is:

In the chart, the affected father (Generation 1) passes the trait to all of his daughters but none of his sons in Generation 2. Furthermore, an affected female passes the trait to both sons and daughters. This pattern is characteristic of an X-linked dominant trait. If it were X-linked recessive, an unaffected mother could not have multiple affected children unless she were a carrier.