Use the following passage to answer the question.
(1) water is something most of us take for granted. (2) if we need a cold drink or want to take a shower, water is there. (3) if we want to water our yards or wash the dishes, water is there. (4) for many parts of the world, however, this is not true. (5) water is not everywhere it's miles away. (6) to get water involves a long walk to and from the source. (7) traditionally it is the job of women and children to spend their days searching for water. (8) then, they gather it to bring back to their homes. (9) sadly, even after that water is found, only some of its clean and safe enough to drink.
(10) a number of groups across the globe have spent decades people get better access to water. (11) one such organization is called water. org (12) it was started in 2009 by actor matt damon and gary white, the co-founder of water partners. (13) what have they accomplished so far

which sentence needs a question mark added to be correct?

a. (1) water is something most of us take for granted.
b. (13) what have they accomplished so far
c. (9) sadly, even after that water is found, only some of its clean and safe enough to drink.
d. (10) a number of groups across the globe have spent decades people get better access to water.