Which aircraft features forward-swept wings?

The X-29A is notable for its forward-swept wings, which are a distinctive feature of its design. This unique wing configuration allows for several aerodynamic advantages, including increased maneuverability and improved control at high angles of attack. The forward-swept wing design facilitates a more favorable airflow over the wing surface, which can lead to enhanced stability and performance in certain flight conditions.

In contrast, the other aircraft mentioned in the choices do not feature forward-swept wings. The XB-70, for instance, has a traditional delta wing configuration optimized for supersonic flight. The XB-15, developed earlier, utilized a conventional straight wing design. The B-1B also employs a conventional wing design that retracts for supersonic flight but does not utilize the forward-swept concept. This highlights the innovative approach and unique role of the X-29A in exploring advanced aerodynamic concepts and technologies.