**Core Concept**
Temporary and permanent hardness of water are caused by the presence of dissolved salts of calcium and magnesium. Temporary hardness, also known as carbonate hardness, arises from the presence of bicarbonates of these ions, which can be removed by boiling and subsequent precipitation as insoluble carbonates. Permanent hardness, on the other hand, is due to the presence of sulfates, chlorides, and nitrates of these ions, which cannot be removed by boiling.

**Why the Correct Answer is Right**
The correct answer involves the use of lime and soda ash (sodium carbonate) to remove both temporary and permanent hardness of water. Lime (calcium hydroxide) reacts with bicarbonates to form insoluble carbonates, which precipitate out, removing temporary hardness. Soda ash reacts with sulfates, chlorides, and nitrates to form insoluble carbonates and bicarbonates, which also precipitate out, removing permanent hardness.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the use of lime and soda ash, which are essential for removing both temporary and permanent hardness.
**Option B:** This option is incorrect because it only mentions the use of soda ash, which is not sufficient to remove permanent hardness.
**Option C:** This option is incorrect because it only mentions the use of lime, which is not sufficient to remove permanent hardness.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the removal of hardness from water using lime and soda ash is an important process in water treatment, and understanding the chemistry behind it is crucial for medical students.

**Correct Answer: C. Lime and soda ash.