Which of the following statements are incorrect?
Statement (I): As a consumer's income increases, the percentage of income spent for food and sundry items decreases, whereas the percentage of income spent for rent, fuel, electricity and clothing remains the same.
Statement (II): The societal marketing period was from 1960 onwards.
Statement (III): Our debt to social anthropology decreases more and more as we use qualitative market research approaches.
Statement (IV): The economic concepts of perfect competition and matching of supply and demand underlie the marketing concept, particularly in relation to the concepts of the price at which goods are sold and quantity distributed.