Choice "B" is correct. A fund is a fiscal and accounting entity with a self-balancing set of accounts recording cash and other financial resources, together with all related liabilities and residual equities or balances, and changes therein. Fund resources are segregated for the purpose of carrying out specific activities (e.g., water and sewer operations) or attaining certain objectives (e.g., providing drinking water and wastewater management services to customers).Choice "c" is incorrect. Fund assets are not limited to cash or cash equivalents. Assets may range from current assets in the governmental funds to all current and non-current assets in the proprietary and fiduciary funds.Choice "d" is incorrect. Combined or combining financial statements are not a prerequisite for fund accounting.Choice "a" is incorrect. Fund resources may be physically comingled but segregated for accounting purposes.