The correct answer is 'Decreased fixed costs due to not having to invest in physical hardware infrastructure.' Cloud computing reduces the need for heavy investments in data centers and physical servers. Instead of spending capital on hardware, this cost becomes a variable cost that depends on the actual usage of services. The PAYG (pay-as-you-go) model allows businesses to pay only for the compute resources they consume, converting many fixed costs to variable costs. 'Decreased operational complexity' is a benefit of cloud migration, but it is not directly a cost advantage. 'Reduced need for in-house IT staff' might lead to cost savings but is not directly related to fixed versus variable costs. 'Zero software licensing costs' is incorrect because while some services could include licenses, there might still be software licensing costs in the cloud depending on the software and licensing model.