What term describes a scale where half steps occur between notes 2-3 and 5-6, like playing all white keys from A to A?

The correct choice is the Aeolian mode, which is known as the natural minor scale. In the context of the given question, the scale described with half steps occurring between the second and third notes as well as the fifth and sixth notes aligns perfectly with the structure of the Aeolian mode. In the case of the A Aeolian scale, which consists of the notes A, B, C, D, E, F, and G, the half steps indeed fall between B and C (the 2nd and 3rd degrees) and between E and F (the 5th and 6th degrees).

This specific arrangement of whole and half steps characterizes the natural minor scale, and when played using all the white keys from A to A, it clearly illustrates the Aeolian mode in action. This is distinct from the other modes listed, each of which has its own unique pattern of whole and half steps that lead to different sounds and musical characteristics.