Spot the error:He hoped that he would learn to quickly run so that he could win the race, and be the best runner.

Explanation

Analysis: The phrase "to quickly run" contains a split infinitive. Although split infinitives are becoming more accepted in modern English, "to run quickly" is still generally preferred for formal writing.Conclusion: This option contains a minor stylistic issue rather than a strict grammatical error.To quickly run: This option is the one to mark due to the minor stylistic issue with the split infinitive. The preferred phrasing for formal writing is "to run quickly."Explanation:"To quickly run" contains a split infinitive; "to run quickly" is generally preferred for formal writing."So" is correctly used to indicate purpose."Could win" is correctly used to indicate potential ability."Best runner" is correctly used as the superlative form.So, the correct answer is A) To quickly run.