Which aircraft is noted for having LAV mounted jump seats?

The choice highlighting the A320 Spaceflex and A321 NEO as having LAV mounted jump seats is correct because both of these aircraft configurations have been specifically designed to optimize cabin space and enhance passenger comfort. The Spaceflex design in the A320 allows for the placement of lavatories and cabin features in a way that provides additional space for these jump seats. This configuration is particularly beneficial for maximizing the number of passengers that can be accommodated on the aircraft without sacrificing safety or comfort.

In contrast, the other options do not accurately reflect the specific aircraft features. The standard A320 does not have the same Spaceflex configuration as the modified version, which is why it cannot be included in the same context. The A321 does have its own set of features, but the inclusion of LAV mounted jump seats is notably tied to the improvements made in the Spaceflex configuration of the A320 and the design of the A321 NEO, which reinforces the accuracy of the selected response.