Which of the following is a sink?
a.) fossil fuels such as coal, oil, and gas.

b.) a location for carbon dioxide storage

c.) the origination point of a gas, such as a volcano

d.) the origination point of a gas, such as the atmosphere

B.) A location for carbon dioxide storage

Explanation:

The word sink is used to describe a carbon sink . A carbon sink is a natural system or artificial deposit that absorb or store carbon dioxide thereby preventing them from going into the atmosphere. The well known natural carbon sinks are sea, plants and soil.

Plants is a vital natural system that absorb carbon dioxide from the atmosphere. The plants uses this carbon dioxide for a process known as photosynthesis.  Some carbon is also transferred to the soil as plants die and decompose. Ocean is a major carbon dioxide storage. The sea dissolves this carbon dioxide.  

Artificial method have been developed to suck up this carbon dioxide from the atmosphere .The carbon dioxide are usually stored underground by a geological formation.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

your spelling is a little off : ]