The correct answer is option 3: 1 and 3 only.

Bioremediation is a technique that uses microorganisms such as bacteria, fungi, and algae to degrade or remove pollutants from contaminated sites. Some advantages of bioremediation in solving pollution problems include:

1. It is a technique for cleaning up pollution by enhancing the same biodegradation process that occurs in nature. Bioremediation is a natural and cost-effective way to clean up contaminated sites. Microorganisms that are naturally present in the environment are utilized to degrade pollutants, which means that bioremediation is a sustainable approach that has minimal impact on the environment.

2. Any contaminant with heavy metals such as cadmium and lead can be readily and completely treated by bioremediation using microorganisms. This statement is incorrect. Bioremediation is effective for treating organic pollutants such as hydrocarbons, pesticides, and solvents. However, heavy metals cannot be biodegraded by microorganisms. Instead, other techniques such as chemical precipitation or ion exchange must be used to remove heavy metals from contaminated sites.

3. Genetic engineering can be used to create microorganisms specifically designed for bioremediation. Genetic engineering can be used to modify microorganisms to enhance their ability to degrade specific pollutants. For example, scientists have engineered bacteria that can break down plastic waste. This approach has the potential to create highly efficient and specialized microorganisms for bioremediation.

In conclusion, the correct answer is option 3: 1 and 3 only. Bioremediation is a natural and cost-effective way to clean up contaminated sites, and genetic engineering can be used to create specialized microorganisms for bioremediation. However, heavy metals cannot be biodegraded by microorganisms, so bioremediation is not effective for treating heavy metal contamination.