Which of the following is a positive overlap that leads to bonding? 

 Overlapping of only same phase creates bonding.  
(I) There is no case of bonding as a positive phase cannot simultaneously make bond with other orbital's positive as well as negative phase 
(II) This creates bonding of p and d orbital.
(III) This creates bonding of two 'p' orbitals. (IV) This is the case of anti-bonding of two 'd' orbitals.