Which rewrite of sentence 15 contributes to clarity with an appositive?

(15) "Greensward" called for the construction of four bodies of water and thirty-six archways and bridges ("History of Central Park").  

 a "Greensward" called for the construction of four bodies of water and thirty-six archways and bridges, which required a large investment ("History of Central Park").  

b "Greensward" called for the construction of four bodies of water (both streams and ponds) and thirty-six archways and bridges ("History of Central Park").  

c "Greensward" called for the construction of four bodies of water (there are now many more) and thirty-six archways and bridges ("History of Central Park").  

d "Greensward" called for the construction of four bodies of water and thirty-six archways and bridges for crossing these waters ("History of Central Park"​