Help me with these quick questions

What factors contribute to the effect an environmental toxin has on the human body?

When the oxygen produced by photosynthetic plants in the water dissolves in the water, which of these is being formed?

Land conservation is a worldwide priority. there are several methods to prevent the loss of land due to a variety of reasons. which method is not a way to conserve land? a) sea walls b) rainwater harvesting c) limits on clear cuts of forests d) cut and burn methods of clearing land