This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Which of the following is the strongest, densest and hardest of pure gold restorative material? 
Select and explain. 
A. Cohesive gold foil, B. Electralloy, C. Goldent, D. Mat foil
A: Cohesive gold foil
Answer: A: Cohesive gold foil 
Explanation: Pure cohesive gold foil restorations will be the strongest, the densest, and the hardest of all types of direct gold restorations. This is due to the greater cohesion between the ingredient leaves (foil) in the completed cohesive gold foil restoration as compared to the ingredient particles of the precipitated gold restorations. Cohesive gold foil restorations will have fewer voids, fewer foreign bodies, and a lesser number of component ingredients (that must be joined together) than restorations made of precipitated gold.
Ref: Marzouk .page 399