Define photosynthesis and explain​

Photosynthesis is the process by which sunlight is used by green plants and certain other creatures to manufacture food from carbon dioxide and water. The presence of the green pigment chlorophyll and the generation of oxygen as a byproduct characterize photosynthesis in plants.

this is more of an opinionated response

explanation:

answer it yourself

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).