Redevelopment includes:
(a) The alteration, improvement, modernization, reconstruction, or rehabilitation, or any combination of these, of existing structures in a project area.
(b) Provision for open-space types of use, such as streets and other public grounds and space around buildings, and public or private buildings, structures and improvements, and improvements of public or private recreation areas and other public grounds.
(c) The replanning or redesign or original development of undeveloped areas as to which either of the following conditions exist.
(1) The areas are stagnant or improperly utilized because of defective or inadequate street layout, faulty lot layout in relation to size, shape, accessibility, or usefulness, or for other causes.
(2) The areas require replanning and land assembly for reclamation or development in the interest of the general welfare because of widely scattered ownership, tax delinquency, or other reasons.