Which intersection forms a hyperbola?
A plane intersects both nappes of a double-napped cone, and the plane does not intersect the vertex.
A plane intersects both nappes of a double-napped cone, and the plane does not intersect the vertex.

A plane intersects only one nappe of a double-napped cone, and the plane is parallel to the generating line of the cone.
A plane intersects only one nappe of a double-napped cone, and the plane is parallel to the generating line of the cone.

A plane intersects only one nappe of a double-napped cone, and the plane is perpendicular to the axis of the cone.
A plane intersects only one nappe of a double-napped cone, and the plane is perpendicular to the axis of the cone.

A plane intersects only one nappe of a double-napped cone, and the plane is not parallel to the generating line of the cone.