Which galaxy classification is NOT part of the Hubble sequence?

A: lenticular

B: elliptical

C: circular

D: spiral

C: circular.

The Hubble sequence is a form of classification of galaxies invented by Hubble in 1926. The sequence divides galaxies into three main categories: lenticular, elliptical and spiral. There is a fourth category that is called irregular, where there are the galaxies that do not fit the characteristics to be included in the three previous categories.

This categorization is the most used even today by both amateurs and astronomers.