Full Detailed In-Depth Explanation:

In Oracle Global Human Resources Cloud, grade rates define the pay values associated with grades, which can be set up with or without steps. When grades are created without steps (i.e., flat grades rather than grade ladders with progression steps), you can still assign rates to them. The system provides multiple methods to achieve this, and the question asks for two correct options.

Option A: Default grade rates are not automatically available upon creating grades unless predefined during initial setup. The system does not inherently provide "default grade rates" for every grade unless explicitly configured, making this option incorrect for grades without steps.

Option B: Adding a grade to a grade ladder implies the grade is part of a stepped structure. However, the question specifies that the grades were created without steps, so this option is not applicable as it assumes a grade ladder with steps exists or needs to be created, which contradicts the scenario.

Option C: The "Manage Grade Rates" task allows you to define salary ranges or specific rates for grades independently of grade ladders. For grades without steps, you can use this task to add rates (e.g., minimum, midpoint, maximum) directly to the grade. This is a valid and straightforward method, making it a correct option.

Option D: This option assumes a stepped structure where rates are added for each step before linking to a grade ladder. Since the grades lack steps, this approach is not feasible in this context.

Option E: The "Manage Grades" task allows you to create or edit grades and, during thisprocess, associate grade rates directly (e.g., by linking to a grade rate range). For grades without steps, you can add rates at the time of grade creation or modification, making this a correct option.

Thus, the two correct options areC(using the Manage Grade Rates task) andE(adding rates via the Manage Grades task). This is supported by Oracle documentation in "Implementing Global Human Resources," which details grade and grade rate setup processes.