Concept:
Stock exchanges are organized marketplaces for trading securities.
Step 1: Number of stock exchanges.
Traditionally, India had 20 recognized stock exchanges across the country.
Step 2: Understanding context.
Though many have become inactive or merged over time, standard textbook reference remains 20.
Step 3: Evaluate options.
- 20 $\rightarrow$ Correct
- 21 $\rightarrow$ Incorrect
- 25 $\rightarrow$ Incorrect
- 24 $\rightarrow$ Incorrect
Step 4: Conclusion.
Thus, there are 20 stock exchanges in the country (as per standard reference).