The activity that puts the most continuous pressure on the lumbar region of your lower back is:

The highest pressure that can be felt on the lumbar region of the spine is when you are in a seated position.There is one more condition when maximum pressure can be felt and that is leaning in forward position with a heavy weight.To avoid this one should not hold weight in this position.In this case the weight should be hold closer to the body to reduce the pressure on the disc and spine.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.

this is a good question! i'll do some research and come back when i have the answer!