The NIST defines cloud computing in part by describing five essential characteristics which are: broad network access, rapid elasticity, resource pooling, measured service and which of the following?

NIST SP 800-145 explicitly names 'on-demand self-service' as one of the five essential characteristics, meaning a consumer can unilaterally provision compute capabilities such as server time and storage as needed, automatically and without requiring human interaction with each service provider. The remaining four are broad network access, resource pooling, rapid elasticity, and measured service.

Standardized auditing is a compliance control, not one of the five essential characteristics defined in NIST SP 800-145.

Separate hardware per customer describes a dedicated tenancy model, which is the opposite of the shared physical infrastructure that underpins most cloud deployments.

Publicly shared resources is not an essential characteristic - NIST describes resource pooling but does not require resources to be publicly shared with all customers.

Multi-tenancy is an implementation pattern common in cloud environments but is not listed as one of the five essential characteristics in NIST SP 800-145.