The correct option is 'Filter'. In LINQ to DataSet, the where clause is used to filter elements from the result set based on a specified condition. It allows you to include only those elements that satisfy the specified condition.

Table Per Type (TPT) mapping strategy in Entity Framework is used for complex inheritance scenarios where each derived type is mapped to its own table, containing only the properties specific to that type. This approach ensures a normalized database schema and allows for efficient querying and data retrieval without redundancy. TPH maps all types in an inheritance hierarchy to a single table, leading to potential data integrity and performance issues. TPC maps each concrete class to its own table, resulting in redundant columns and denormalized data. TPE is not a standard mapping strategy in Entity Framework.

In a Code-First approach with Entity Framework, database schema changes are managed through migrations. When developers modify the application's data model, Entity Framework generates migration files that represent these changes. Developers can then apply these migrations to update the database schema incrementally. Entity Framework tracks the history of migrations applied to the database, allowing developers to roll back changes if needed. This approach enables developers to evolve the database schema alongside the application's data model while preserving existing data.

Entity Framework (EF) stands for Entity Framework. It is an Object-Relational Mapping (ORM) tool provided by ADO.NET, facilitating developers to work with relational data as domain-specific objects, eliminating the need for most of the data access plumbing code.

The [Key] attribute in Entity Framework is commonly applied to specify the identity property of an entity, indicating the property that uniquely identifies each instance of the entity.

In scenarios where multiple users are modifying the same data concurrently, concurrency control mechanisms such as locking can help ensure data integrity by preventing conflicting modifications from occurring simultaneously.

Monitoring the number of connections in use and the connection wait time is essential to understand the current utilization of the connection pool and identify any potential bottlenecks. By adjusting the pool size settings, such as "Max Pool Size" and "Min Pool Size," and evaluating parameters like "Connection Lifetime," you can optimize the connection pool for better performance.

The correct option is Where and Select. You would use the Where operator to filter the products that are in stock and have a price greater than $50, and then use the Select operator to project the results into a new collection containing only the required product information. This combination allows you to filter and select the desired products in a single query.

In SQL, the SELECT statement retrieves data from one or more tables in a database. It allows you to specify which columns to retrieve and may include conditions to filter rows. The fundamental purpose of the SELECT statement is to fetch data from the database tables.

Recursive queries in LINQ can cause performance degradation, especially with large datasets, due to the iterative nature of their execution. It's recommended to avoid them for better performance.