Answer:
a. valuable; rare
Step-by-step explanation:
There are various examples of capabilities like
1. Frequent flyer programs are nothing but while booking an online flight you just need to sign up so that the chances of earning reward points could be high
2. The ticket kiosks refer to the self service in which you can purchase the tickets related to the entertainment
3. E-ticketing is online ticketing which you can store online instead of keeping it with you in a paper form
These are valuable examples but there are no longer rare
Hence, the first option is correct