Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following? 1. Brakes of motor vehicles 2. Engines of motor vehicles 3. Microwave stoves within homes 4. Power plants 5. Telephone lines Select the correct answer using the code given below.

Option (b) is correct because magnetite particles are primarily generated as particulate matter through high-temperature combustion in vehicle engines and power plants, as well as through frictional wear in braking systems. Option (d) is the most tempting wrong choice, but it is incorrect because microwave stoves and telephone lines utilize electromagnetic fields and do not physically emit magnetite particles into the environment. The core concept tested is the identification of anthropogenic sources of magnetic nano-particulates and their classification as environmental pollutants.