According to the ServiceNow documentation1, a rate card is a table that defines the hourly cost of labor for different roles or resources. A project rate is a fixed rate that is applied to all resources assigned to a project, regardless of their roles or individual rates. Both of these can be used to calculate the planned cost of a resource plan by multiplying the hours allocated to each resource by the corresponding rate. The other options are incorrect because:
A: Demand rate: A demand rate is a rate that is applied to a demand, not a resource plan. It is used to estimate the cost of fulfilling a demand before it is converted into a project2.
C: Default rate: A default rate is a rate that is applied to a resource when no other rate is specified. It is not a valid option for calculating the planned cost of a resource plan, as it is only used as a fallback option3.
1:
https://docs.servicenow.com/bundle/vancouver-it-business-management/page/product/resource-management/con
https://docs.servicenow.com/bundle/vancouver-it-business-management/page/product/demand-management/conc
https://docs.servicenow.com/bundle/vancouver-it-business-management/page/product/resource-management/con