Answer:
b. some firms exit, industry supply decreases, market price rises.
Step-by-step explanation:
A perfect competitive industry is characterised by many buyers and sellers of homogenous goods and services. There are no barriers to entry or exit of firms.
If firms are making economic loss is the short run, in the long run, firms leave the industry. This leads to a fall in supply and prices rise as a result. In the long run, firms in a competitive industry earn zero economic profit.
I hope my answer helps you