A European call option and put option on a non-dividend-paying stock both have a strike price of $20 and an expiration date in three months. Both sell for $3. The risk-free interest rate is 10% per annum, the current stock price is $19. Identify the arbitrage opportunity open to a trader.

Nextdoor is an instant messaging application for smartphones. new smartphone users find it easier to connect with friends and relatives through this mobile app when compared to other similar instant messaging applications. hence, it has the largest user base in the industry. thus, nextdoor app's value has increased primarily due to itsa. learning curve effects. b. economies of scale. c. economies of scope. d. network effects.