A murabahah transaction is deemed lawful if:

 a. 

both tangible and non-tangible goods subject to murabahah are lawful, real and have commercial value.

 b. 

the buyer is aware of the original cost price of the goods and any additional costs incurred after sign the contract

 c. 

the margin of profit is mutually predetermined by the parties at any time of the contract.

 d. 

all of the above