For the following arrangements, explain whether they are operating or finance lease transactions: 

(a) Entity A leases an asset to entity B, and obtains a loan from a financial institution using the lease rentals and asset as collateral. Entity A sells the asset subject to the lease and the loan to a trustee, and leases the same asset back. 

(b) Entity A enters into an agreement to buy petroleum products from entity B. The products are produced in a refinery built and operated by entity B on a site owned by entity A. While entity B could provide the products from other refineries that it owns, it is not practical to do so. Entity 8 retains the right to sell products produced by the refinery to other customers, but there is only a remote possibility that it will do so. The arrangement requires entity A to make both fixed, unavoidable payments, and variable payments based on input costs at a target level of efficiency to entity B. 

(c) Entity A leases an asset to entity B for its entire economic life, and leases the same asset back under the same terms and conditions as the original lease. The two entities have a legally enforceable right to set off the amount owing to one another, and an intention to settle these amounts on a net basis. 

(d) Entity A enters into a non-cancellable four year lease with entity B for an asset with an expected economic life of ten years. Entity A has an option to renew the lease for a further four years at the end of the lease term. At the conclusion of the lease arrangement, the asset will revert back to entity B. In a separate agreement, entity B is granted a put option to sell the asset to entity A should its market value at the end of the lease be less than the residual value.