At the beginning of a stressed syllable, voiceless plosives become aspirated in English in the output. But universally, aspirated plosives are more marked than unaspirated plosives. What can be the position constraints to make a tableau (quasi and ranked) to derive this result.
This can be disposed of with a contrast-enhancement constraints, which makes the output of /p/ vs. /b/ more perceptually salient (there being more phonetic cues to identify the distinction when voiceless stops are aspirated). Here is one of hundreds of ways to integrate contrast-enhancement. The claim that aspirated stops are mark is itself a highly contentious and under-supported claims that pre-dates OT by decades, so the alternative is that what is "marked" (unusual) is contrasting aspirates and non-aspirates, and given a contrast, aspirates "bear the mark" in the Trubetzkovian sense.