Based on the following data, the single-factor productivity for input of labour is (choose all that apply) Output: 9,000 units Multi-factor productivity for the combined inputs of labour and materials: 2.0 unit per dollar of input Single-factor productivity for the input of materials: 3.0 unit per dollar of input twice as big as the single-factor productivity for the input of materials twice as big as multi-factor productivity for the combined inputs of labour and materials three times as big as multi-factor productivity for the combined inputs of labour and materials three times as big as the single-factor productivity for the input of materials