WHICH OF THE FOLLOWING IS TRUE ABOUT THE ASSUMPTIONS UNDERLYING BASIC CVP ANALYSIS? 1. ONLY SELLING PRICE IS KNOWN AND CONSTANT 2. ONLY SELLING PRICE AND VARIABLE COST PER UNIT ARE KNOWN AND CONSTANT 3. SELLING PRICE, VARIABLE COST PER UNIT, FIXED COST PER UNIT, AND TOTAL FIXED COSTS ARE KNOWN AND CONSTANT 4. ONLY SELLING PRICE, VARIABLE COST PER UNIT, AND TOTAL FIXED COSTS ARE KNOWN AND CONSTANT