What would you recommend to improve performance?

View the Exhibit and examine the PL/SQL code.
The code takes a long time to execute. What would you recommend to improve performance?

A.
using NOT NULL constraint when declaring the variables

B.
using the BULK COLLECT option for query instead of cursor

C.
using WHILE.. END LOOP instead of FOR .. END LOOP

D.
using the SIMPLE_INTEGER data type instead of the NUMBER data type