Concept:Precautionary demand for money refers to cash held to meet unexpected or emergency expenses.Explanation:This demand is mainly influenced by the level of income, because higher income enables people to set aside more money for unforeseen needs.Other factors, such as availability of credit and the rate of interest, play a secondary role.Thus, among the given options, the precautionary demand for money is determined by the level of income.Answer:C. the level of income