c
(c) \(\lambda = \frac{h}{p}\)==>\(\lambda - \frac{{0.5}}{{100}}\lambda = \frac{h}{{p + \Delta p}}\)

==>\(\frac{{199\lambda }}{{200}} = \frac{h}{{p + \Delta p}} = \frac{{199}}{{200}}\frac{h}{p}\)

==> \(p + \Delta p = \frac{{200}}{{199}}p\)

==> \(p = 199\, \Delta p\)