Option 1 -> "will" doesn't follow backshift rules needed after the past tense "asked."
Option 2 -> "could" correctly follows reported speech rules, shifting from "can" in the original question.
Option 3 -> "would" would only work if the original question used "will," but asking about ability uses "can."
Option 4 -> "should" implies obligation/advice rather than asking about ability or possibility.
Hence, Option 2: could -> When converting direct speech ("Can you complete...?") to reported speech after a past tense reporting verb ("asked"), "can" shifts to "could" following standard backshift rules in English grammar -> correct