An isoquant is best defined as a curve representing:

1. An isoquant shows all combinations of inputs that are capable of producing the same level of output. 2. The producer is indifferent among the combinations on one isoquant, which is why it is also called an equal-product curve. 3. So the correct definition is all input combinations giving the same output. 4. Combinations costing the same outlay describe an iso-cost line, not an isoquant, and the other options misstate the concept. _Source: ICAI BoS CA Foundation Paper 4 Business Economics, Ch 3 Unit I "Theory of Production", p.22_