The correct answer is granite. Granite is a hard, igneous rock that is composed of quartz, feldspar, and mica. It is the most common type of intrusive igneous rock. Granite is very strong and durable, and it is often used in construction.
Chalk is a soft, sedimentary rock that is composed of calcium carbonate. It is formed from the remains of marine organisms, such as algae and coral. Chalk is not very strong, and it is easily eroded.
Slate is a metamorphic rock that is formed from shale. It is a hard, dense rock that is often used in roofing and flooring. Slate is not as strong as granite, but it is stronger than chalk.
Sandstone is a sedimentary rock that is composed of sand grains. It is a relatively soft rock that is easily eroded.
Therefore, the stone whose crushing strength is maximum is granite.