To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) Using Join one can achieve M:M relationship - This option is incorrect. Joins are used to establish relationships between two tables, but they cannot directly achieve a many-to-many (M:M) relationship. To achieve an M:M relationship, an intermediate table or junction table is usually required.
Option B) Explicit Join Fields are read-only - This option is correct. In a join, the explicit join fields are read-only, meaning that you cannot modify the values of these fields directly.
Option C) Explicit joins need to be created in Tools - This option is correct. In most cases, explicit joins need to be created using tools or design-time configuration. This allows you to define the join conditions and specify how the data from the joined tables should be retrieved.
Option D) Joins are between two applets - This option is incorrect. Joins can be established between two tables or data sources, not necessarily limited to applets. An applet is a user interface component that interacts with the data in a table or data source.
The correct answer is B, C. Explicit join fields are read-only, and explicit joins need to be created in tools or design-time configuration.