Possible supply contract types are given in the textbook to be: i$)$ buyback contracts, ii$)$ revenue$-$sharing contracts and iii$)$ quantity flexibility contracts.

a$)$ Specify one contract type from the above list for which the basic feature$($s$)$ of the contract would have a positive impact in terms of planning and coordinating supply and demand along the supply chain.

b$)$ Specify one contract type from the above list for which the basic feature$($s$)$ of the contract would have a negative impact in terms of planning and coordinating supply and demand along the supply chain.