There are many physical advantages of administering a dual spinal epidural or walking epidural during childbirth like walking epidural uses smaller needles and a system for administering an anesthetic, it also permits the woman to move freely during labor, and it has fewer effects than a traditional epidural. The disadvantage is a walking epidural cost less to administer.
The bulb! I hope this helps :)
A/C/D: All of these answers are positive effects, of human water use.
By process of elimination it must be (B) Also the run off is basically stripping the soil of the nutrients a farmer would need to grow crops, so this is incredibly bad - but a problem easily fixed.