To solve this question, the user needs to know the concept of self-join in database management systems.

A self-join is a regular join, but the table is being joined with itself. This means that we are using a single table to compare rows within the same table.

Option A is incorrect because a left and right join is not referred to as a self-join.

Option B is incorrect because the number of tables being joined does not determine whether a self-join is being used or not.

Option D is incorrect because a regular join between two tables is not referred to as a self-join.

Therefore, the correct answer is:

The Answer is: C. We are joining table to itself.