Final answer:
Archive storage is the most appropriate option for the fitness application company's infrequently accessed data due to its cost-effectiveness and suitability for long-term archiving.
Step-by-step explanation:
The fitness application company is looking for a cost-effective storage solution to manage their large and growing data set, particularly for data older than 30 days which is accessed infrequently. Since users do not need this historical data immediately, the company can benefit from using a storage option that is designed for long-term data archiving and offers low-cost storage with higher retrieval times and costs.
Of the choices provided, Archive storage would be the best suited option for storing infrequently accessed data. Archive storage is optimized for data that is accessed less frequently, typically for backups and long-term storage, and is great for reducing storage costs while accommodating the longer retrieval times that users are willing to wait for.