The correct answer is A. Hydraulic lime.
Hydraulic lime is a type of lime that can set and harden underwater. It is made by burning limestone at a lower temperature than quicklime, which results in a lime that contains some unhydrated calcium oxide. This unhydrated calcium oxide reacts with water to form calcium hydroxide, which is what gives hydraulic lime its ability to set underwater.
Fat lime is a type of lime that is rich in calcium oxide. It is made by burning limestone at a high temperature, which results in a lime that is almost pure calcium oxide. Fat lime is not hydraulic, meaning that it cannot set underwater.
Quick lime is a type of lime that is made by burning limestone at a very high temperature. This results in a lime that is almost pure calcium oxide. Quick lime is not hydraulic, meaning that it cannot set underwater.
Pure lime is a type of lime that is made by burning limestone at a very high temperature. This results in a lime that is almost pure calcium oxide. Pure lime is not hydraulic, meaning that it cannot set underwater.
Hydraulic lime is the best type of lime to use for construction of structures under water because it is the only type of lime that can set underwater.