Explanation:

The odd one out in this group is Slaked lime (option D).

Marble (option A):
- Marble is a type of metamorphic rock that is composed of recrystallized carbonate minerals, typically calcite or dolomite.
- It is commonly used in construction, sculpture, and decorative applications.

Chalk (option B):
- Chalk is a soft, white, porous sedimentary rock that is a form of limestone.
- It is mainly composed of the mineral calcite and is used for writing and drawing on blackboards, as well as in construction and agriculture.

Limestone (option C):
- Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3).
- It is formed from the remains of marine organisms such as coral and shells and is commonly used in construction, agriculture, and as a raw material for various industrial processes.

Slaked lime (option D):
- Slaked lime, also known as calcium hydroxide (Ca(OH)2), is a chemical compound.
- It is obtained by adding water to quicklime (calcium oxide) and is commonly used in various applications such as in the preparation of mortar, plaster, and as a pH regulator in water treatment.

Reasoning:
- Marble, chalk, and limestone are all types of rocks that are composed mainly of calcium carbonate.
- They are all related to each other and share similar properties and uses.
- Slaked lime, on the other hand, is a chemical compound and not a type of rock.
- It has different properties and uses compared to the other options.
- Therefore, slaked lime is the odd one out in this group.