Initial:

Flour(F):Water(W):Sugar(S)=7:4:1

Now, let's separate the ratios for convenience.

F:W=7:4 ; F:S=7:1

Now, bring both ratios to the same denominator by multiplying,

F:W=7:4 ; F:S=28:4

Now, quantity of F in F:W is doubled,

F:W=14:4

Now, quantity of F in F:S is halved,

F:S=14:4

Since the denominators are equal, we can write the new ratio together as,

F:W:S=14:4:4

We see that water and sugar are both in equal quantities in the ratio. Hence, if we add 8 cups of water, we have to add 8 cups of sugar too.

ANS. C

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