A- Med-arb clause: This refers to a clause where mediation is attempted first before resorting to arbitration. The given clause directly mentions arbitration without any mediation step.
B- Multi-tier clauses: These involve multiple dispute resolution options, like negotiation followed by arbitration or litigation. This clause only specifies arbitration.
D- Sole option clause: This is a valid arbitration clause where arbitration is the only option for dispute resolution. However, the current clause has a defect.
The defect lies in the arbitrator's qualifications. While requiring multilingualism is reasonable, demanding legal education in three jurisdictions (Turkey, Italy, and USA) might be impractical. Finding an arbitrator with such a specific background could be difficult and delay the process.

Therefore, this clause is defective due to the overly specific arbitrator qualifications hindering the smooth operation of the arbitration process.