To answer this question, we need to understand the concepts of sequences in the context of databases.

A sequence is an object in a database that generates a sequence of unique values. In Oracle, two pseudo columns are used in conjunction with sequences: NEXTVAL and CURRVAL.

Statement A: You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value. This statement is true. The NEXTVAL pseudo column allows you to obtain the next possible value from a sequence without affecting the further values to be generated. It effectively increments the sequence by 1 and returns the next value.

Statement B: You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence. This statement is also true. The CURRVAL pseudo column allows you to obtain the current value generated from a sequence without affecting the further values to be generated. It does not increment the sequence; it only returns the current value.

Statement C: You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence. This statement is incorrect. The NEXTVAL pseudo column does not retrieve the value from the sequence; it only returns the next possible value without affecting the sequence.

Therefore, the correct answer is option D: Both A and B. Both statements A and B correctly describe the usage of NEXTVAL and CURRVAL pseudo columns in relation to sequences in Oracle databases.