The one with the highest pH would be a solution with 100 mL of water and also 20 mL of 0.1 M NaOH is added. Solutions without buffers would have the highest pH since the resistance to change is very low. Hope this answers the question.
D. Synthesis cause A + B --> AB
Equation: 2Na + Cl2 --> 2NaCl
These 5 metals are: zinc,copper,tin,bronze,nickel