Which of the following pollutants is known to be inhaled and can also enter the body through the skin?

Particulate matter is a mixture of tiny solid particles and liquid droplets suspended in the air, and it presents a significant concern for human health due to its ability to be inhaled into the lungs. These particles can also transfer some chemicals through the skin, entering the body directly.

Carbon monoxide, a colorless and odorless gas, is widely recognized for being inhaled and can be harmful when it binds to hemoglobin in the blood, preventing oxygen transport. However, it is not known to enter the body through the skin.

Ozone, while harmful to the respiratory system when inhaled, primarily affects health via the lungs and does not have a significant route of entry through the skin.

Given this information, particulate matter is unique in its ability to enter the body via both inhalation and potential skin absorption, making the collective consideration of all these pollutants appropriate in this context. Thus, "all of the above" as the correct answer reflects the understanding that while methods of entry may vary, all listed pollutants can contribute to the overall inhalation exposure.