Which of these human activities is most likely to cause the excessive growth of algae in a lake or ocean?
The use of chemical fertilizers that are carried by runoff into rivers, then lakes and oceans.
The spraying of herbicides that kill weeds, then the herbicide running off the land and being carried to the lake/ocean.
The mining of fossil fuels, which requires drilling underground and possibly effecting the groundwater.
The logging of forests which results in erosion.