A. Medical waste is generally collected by gravity chutes, carts, or pneumatic tubes,
each of which
have heir own advantages and disadvantages.
when each is used as the subject for a verb then the verb should be singular, here
"have"-is plural therefore this option is wrong!
B.
Collected by gravity chutes, carts, or pneumatic tubes, each of which has its own advantages and disadvantages, is medical waste.
the modifier "collected by gravity chutes....tube" should be followed by the entity its modifying (i.e medical waste)
this option has a
modifier errorC. Medical waste is generally collected by gravity chutes, carts, or pneumatic tubes
are also used, each of which has its own advantages and disadvantages.
the phrase
"are also used" is redundant and unnecessary , the sentence is fine without the phrase
D. Medical waste is generally collected by gravity chutes, carts, or pneumatic tubes,
each of which
has its own advantages and disadvantages.
has refers to the singular subject each and this sentence does not contain any other errors! therefore this is the right answer!E. There are advantages and disadvantages for each means of collection of medical waste, including gravity chutes, carts, and pneumatic tubes.
this option creates a meaning error! this option means that gravity chutes, carts and pneumatic tubes itself advantages and the disadvantages
the option however means to say that gravity chutes, carts and pneumatic tubes have advantages and disadvantages they themselves are not the advantages and disadvantages.
therefore option D is the correct option!! _________________