Explanation
A - Backups are encrypted andstored in Oracle Cloud Infrastructure Object Storage, and can be restored as new volumes to any availability domain within the same region they are stored.
D- You can restore a block volume backup to a larger volume size. To do this, check Custom Block Volume Size (GB), and then specify the new size. You can only increase the size of the volume, you cannot decrease the size.

Explanation
When creating a compartment, you must provide a name for it (maximum 100 characters, including letters, numbers, periods, hyphens, and underscores) that is unique within its parent compartment. You must also provide a description, which is a non-unique, changeable description for the compartment, from 1through 400 characters.
After creating a compartment, you need to write at least one policy for it, otherwise no one can access it (except administrators or users who have permissions set at the tenancy level). When creating a compartment inside anothercompartment, the compartment inherits access permissions from compartments higher up its hierarchy.
When you create an access policy, you need to specify which compartment to attach it to. This controls who can later modify or delete the policy. Dependingon how you've designed your compartment hierarchy, you might attach it to the tenancy, a parent, or to the specific compartment itself.

Explanation
With multipart upload, you split the object you want to upload into individual parts. Individual parts can be as large as 50 GiB or as small as 10 MiB. (Object Storage waives the minimum part size restriction for the last uploaded part.) Decide what part number you want to use for each part. Part numbers can range from 1 to
10,000. You do notneed to assign contiguous numbers, but Object Storage constructs the object by ordering part numbers in ascending order.
The maximum size for an uploaded object is 10 TiB
While a multipart upload is still active, you can keep adding parts as long as thetotal number is less than
10,000.
https://docs.cloud.oracle.com/en-us/iaas/Content/Object/Tasks/usingmultipartuploads.htm