Which statement is true about this code?

The Orders database table uses Order_id as its primary key. You have written the following code
to use in the Orders block of a form:
SELECT orders_seq.NEXTVAL
INTO :orders.order_id
FROM SYS.dual;

Which statement is true about this code?

A.
If you place thisCodeina trigger that fires when the record isinsertedinto the database, you will
likely have more gapsinOrderIDs than if you use the sequence as a default value for the item.

B.
If you place this codeina trigger, you should ensure that Order_Id hasitsrequiredproperty set to
Yes.

C.
If you place this codeina trigger, you should ensure that Order_Id has its Database Item
property set to No.

D.
If the named sequence does not exist, it is automatically created the first time the code is
called.

E.
You should place this code aina database trigger to minimize the gapsinOrder IDs.

F.
You should place this codeinPre-insert trigger to minimize the gapsinOrder IDs.

G.
You should place this codeina Post_insert trigger to minimize the gapsinOrder IDs.

Explanation:
Assigning Sequence Numbers to Records
You will recall that you can assign default values for items from an Oracle sequence, to
automatically provide unique keys for records on their creation. However, if the user does
not complete a record, the assigned sequence number is “wasted.”
An alternative method is to assign unique keys to records from a Pre-Insert trigger,
just before their insertion in the base table, by which time the user has completed the
record and issued the Save.
Assigning unique keys in the posting phase can:
* Reduce gaps in the assigned numbers
* Reduce data traffic on record creation, especially if records are discarded before
saving
Example
This Pre-Insert trigger on the ORDERS block assigns an Order ID from the sequence
ORDERS_SEQ, which will be written to the ORDER_ID column when the row is
subsequently inserted.
SELECT ORDERS_SEQ.nextval
INTO :ORDERS.order_id
FROM SYS.dual;