Dissolved organic solids are a common component of wastewater and can pose challenges in the treatment process. These solids are typically made up of organic compounds such as proteins, carbohydrates, and fats that are present in the wastewater stream. Removing these dissolved organic solids is important to ensure the treated water meets the required quality standards before it is discharged or reused.

There are several methods available for the removal of dissolved organic solids in wastewater treatment. These methods include coagulation, hypochlorination, reverse osmosis, and others. However, in this case, the correct answer is option 'C', reverse osmosis.

Reverse osmosis (RO) is a membrane filtration process that uses a semi-permeable membrane to separate dissolved solids from water. It works by applying pressure to the wastewater stream, forcing the water molecules to pass through the membrane while retaining the dissolved solids. The membrane used in reverse osmosis has very small pores that can effectively remove dissolved organic solids, along with other contaminants such as salts, minerals, and microorganisms.

Reverse osmosis is particularly effective in removing dissolved organic solids because the membrane has a high rejection rate for these compounds. The size of the organic molecules determines whether they can pass through the membrane or not. Typically, molecules with a molecular weight of more than 200 Daltons are effectively rejected by the membrane, while smaller molecules can pass through.

Other methods such as coagulation and hypochlorination are primarily used for the removal of suspended solids and disinfection, respectively. Coagulation involves the addition of chemicals that destabilize and aggregate suspended particles, allowing them to settle or be removed by filtration. Hypochlorination, on the other hand, involves the addition of chlorine-based compounds to disinfect the wastewater and kill microorganisms.

In conclusion, dissolved organic solids in wastewater can be effectively removed by reverse osmosis. This method utilizes a semi-permeable membrane to separate the dissolved solids from the water, resulting in a treated effluent with reduced organic content. Other methods such as coagulation and hypochlorination are not as effective in removing dissolved organic solids and are primarily used for other purposes in the wastewater treatment process.