According to the brønsted-lowry definition, in which of the following reactions does water act as an acid?
a) hc2h3o2(aq) + h2o(l) → h3o+(aq) + c2h3o2-(aq)
b) h2o(l) + no2-(aq) → hno2(aq) + oh-(aq)
c)hcl + h2o(l) → h3o+(aq) + cl-(aq)
d)h2o(l) + nh4+(aq) → h3o+(aq) + nh3(aq)