Verified Answer :

\(\frac{-1}{8c} =2\)
This requires that  c ≠ 0 , meaning c≠0
\(\frac{-1}{8c} =2\)
Multiply by x to eliminate var in denominator
\(\frac{ ot c*(-1)}{ 8 ot c} =c*2\)
\(\frac{-1}{8} =c*2\)
Common denominator  is 8 
\(\frac{ ot 8(-1)}{ ot 8} =8c*2\)
\(-1=8c*2\)
\(-1=16c\)
\(x=-16\)
The answer is: b. -16