※This sample exam is different from those that appear in the actual OSS-DB Exam.
The PostgreSQL License is based on BSD, allowing distribution of source code free of charge; no special restrictions apply to its modification.
Distribution of source code does not require any obligation to display the license agreement, nor is there an obligation to disclose modified code. You may also charge a fee for the distribution of the product if you so wish.
New functionality may be requested of the global development community, but that is not the only way to introduce new functionality.
As the Japan based PostgreSQL User Group is a community based user group, they do not provide services such as product modification.
Therefore, the correct answer is E.