They are all living organisms
Oddly worded, but oxygen is mostly transported bound the the protein hemoglobin
I believe that the correct match will be;
Prominences- A
Sunspots - B
Solar flares - C
Convection -D
Prominence is a large, bright feature extending outward from the Sun's surface. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's hot outer atmosphere, called the corona.
Sunspots are darker, cooler areas on the surface of the sun in a region called the protosphere. Solar flares are large eruptions of electromagnetic radiation from the sun lasting from minutes to hours.
