During the Data Import Process in Oracle,if Some of the Spreadsheet

Multiple Choice

During the data import process in Oracle,if some of the spreadsheet cells in a column of the source data are empty,________.

A) you must put some data in them before importing
B) you must not specify this column as a foreign key later
C) you must ensure the data type for this column is numeric
D) you must check the "Nullable" box in the wizard