Concept:The idiom "does not know the half of it" means a person knows only a part of a situation and underestimates how serious or difficult it truly is.Explanation:The expression suggests that Kola is aware the case involves some difficulty, but he is not fully aware of its real magnitude.The phrase "not know the half of it" means the full reality is worse or more challenging than what appears at first.Therefore, the case was not merely a little difficult; it was far more challenging than Kola could possibly have imagined.Answer:C. it was even more difficult than Kola could imagine.