Which should humans do to ensure that the environment is healthy for all living things? select one of the options below as your
a. test water
b. test the air
c. recycle wastes
d. all the above

All of the above are important in order to keep our environment healthy! this is how:

1) Testing water will help us know whether the water is clean - and if we find out that it isn't, we will be able to do something about it!
2) testing the air will have the same effect as in 1)
3) recycling waste will make us produce less waste - and waste is bad for the environment!

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen