**Explanation:**

The correct answer is option 'A' (Only 1).

**Photochemical Smog:**
- Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants such as nitrogen oxides and volatile organic compounds (VOCs) in the atmosphere.
- Sulphur dioxide (SO2) does not directly contribute to the formation of photochemical smog. It is primarily produced by the burning of fossil fuels such as coal and oil, and is a major contributor to air pollution and acid rain.

**Acid Rain:**
- Acid rain is caused by the emission of sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere, which react with water vapor to form sulfuric acid and nitric acid.
- Sulphur dioxide (SO2) is a major contributor to acid rain. It is released into the atmosphere from the burning of fossil fuels, particularly coal and oil, as well as from industrial processes such as smelting and power generation.

**Death of Vegetation:**
- Sulphur dioxide (SO2) is harmful to vegetation and can cause damage to plants.
- It can enter plant stomata and react with water to form sulfurous acid, which can damage plant tissues and interfere with various physiological processes.
- High levels of sulphur dioxide can lead to leaf injury, reduced growth, and even death of vegetation.

**Loss of Biodiversity in Aquatic Ecosystem:**
- Sulphur dioxide (SO2) can have detrimental effects on aquatic ecosystems.
- When sulphur dioxide is released into the atmosphere, it can be transported over long distances and deposited into water bodies through rainfall or dry deposition.
- The acidification of water bodies due to sulphur dioxide can lead to a decrease in the pH levels, making the water more acidic.
- This change in pH can have harmful effects on aquatic organisms, leading to a loss of biodiversity in aquatic ecosystems.

**Damage to Buildings:**
- Sulphur dioxide (SO2) can contribute to the damage of buildings and structures.
- It can react with moisture in the air to form sulphuric acid, which can corrode metals, deteriorate concrete and stone, and cause discoloration and damage to buildings and structures.

In conclusion, sulphur dioxide (SO2) contributes to all of the problems mentioned above, except for photochemical smog. It is important to address the emissions of sulphur dioxide and other air pollutants to mitigate these environmental and health impacts.

C