Which reaction is an example of an endothermic reaction?

Photosynthesis

Explanation:

An endothermic reaction is any chemical reaction that absorbs heat from its environment. In photosynthesis, energy is absorbed from the sun to make glucose and oxygen.  

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.