Final answer:
Ynah and Aola should use a heterogeneous database to ensure compatibility between different operating systems, Windows and Macintosh. They can choose standard file formats or cross-platform database software that both systems support.
Step-by-step explanation:
To ensure compatibility between different operating systems, Ynah and Aola should work with a heterogeneous database. This type of database can operate across various platforms and can be used by different kinds of database management systems (DBMS), which may be necessary since Ynah uses Windows and Aola uses Macintosh. It's necessary to choose a database file format that is supported on both operating systems to avoid compatibility issues. Standard file formats like .csv (Comma Separated Values) or cross-platform database software like MySQL or SQLite can be used to achieve this. When sending database files, they may also consider using cloud-based services or web applications to further ensure compatibility and accessibility.