The correct answer is option 1, CFL Lamp. This is because CFL lamps, also known as compact fluorescent lamps, contain a small amount of mercury. When these lamps are broken or not disposed of properly, the mercury can be released into the environment. Mercury is a toxic substance that can contaminate air, water, and soil, leading to pollution.

Option 2, Automobile Battery, is not primarily responsible for mercury pollution. While automobile batteries do contain lead, which is a concern for environmental pollution, they do not typically contain mercury.

Option 3, Polymer, is not directly responsible for mercury pollution. Polymers are large molecules made up of many repeated subunits, and they do not contain mercury as an inherent component.

Option 4, Diesel Engine, is not primarily responsible for mercury pollution. While diesel engines can emit air pollutants, such as nitrogen oxides and particulate matter, they do not directly release mercury into the environment.

In conclusion, the primary cause of mercury pollution is option 1, CFL lamps.