Explanation:

All the statements are correct. 

Geoengineering schemes are projects designed to tackle the effects of climate change directly, usually by removing CO2 from the air or limiting the amount of sunlight reaching the planet's surface i.e. greenhouse gas removal and solar radiation management respectively.
Solar radiation management methods may include:

Surface-based: for example, protecting or expanding polar sea ice and glaciers, using pale-colored roofing materials, attempting to change the oceans' brightness, or growing high-albedo crops.
Troposphere-based: for example, marine cloud brightening, which would spray fine sea water to whiten clouds and thus increase cloud reflectivity.
Upper atmosphere-based: creating reflective aerosols, such as stratospheric sulfate aerosols, specifically designed self-levitating aerosols, or other substances.
Space-based: space sunshade—obstructing solar radiation with space-based mirrors, dust,