What is the burden of proving that the neglect leading to default was excusable?

Under the discretionary provision, the moving party has the burden to show "that the neglect leading to default was excusable. 'Neither mistake, inadvertence, or neglect will warrant relief unless upon consideration of all the evidence it is found to be of the excusable variety. [Citations.] To entitle [a party] to relief the acts which brought about the default must have been the acts of a reasonably prudent person under the same circumstances.' " (Jackson v. Bank of America (1983) 141 Cal.App.3d 55, 58, italics added.)