The correct answer is A. Lead sulphate.
Lead sulphate is a relatively insoluble salt. It has a solubility of only 0.006 grams per liter of water at 25 degrees Celsius. This means that only a very small amount of lead sulphate will dissolve in water.
Zinc sulphate, potassium sulphate, and sodium sulphate are all much more soluble in water. Zinc sulphate has a solubility of 25 grams per liter of water at 25 degrees Celsius. Potassium sulphate has a solubility of 13 grams per liter of water at 25 degrees Celsius. Sodium sulphate has a solubility of 41 grams per liter of water at 25 degrees Celsius.
The solubility of a salt is determined by the strength of the ionic bonds between the ions in the salt. The stronger the ionic bonds, the less soluble the salt will be. Lead sulphate has very strong ionic bonds, which is why it is so insoluble in water. Zinc sulphate, potassium sulphate, and sodium sulphate have weaker ionic bonds, which is why they are more soluble in water.