Part C has an error, hence, option 3 is the right answer. Key Points As per the rule, with a superlative degree of an adjective, 'the' must be used. Here, 'best' is superlative, hence, 'a' must be replaced with 'the'. Additional Information Regression: a return to a former or less developed state. If something is over a particular amount, measurement, or age, it is more than that amount, measurement, or age. Example: I carried out a survey of over a thousand patients. We use the article 'a' before 'thousand' when we are referring to the number equivalent to the product of a hundred and ten; Correct Sentence: The regression model is used by just over a thousand FMCG companies, but it offers the best of predictive analysis and process improvement analysis.