Instantiating a class template with a type that doesn't meet the template's requirements would result in a compilation error. Templates rely on the types they are instantiated with to adhere to specific criteria. If those criteria aren't met, the compiler will produce an error message indicating the discrepancies.

In C++, the logical AND (&&) operator employs short-circuit evaluation. If the left operand is false, the right operand isn't evaluated because the overall result will already be false.

The get() method is used to read a single character from a file in C++. While extract() is not a standard method for this purpose, fetch() and pull() are not associated with file reading in the standard C++ library.

In C++, when a non-member function is declared as a friend of a class, it can access both private and protected members of that class. Public members are accessible to all functions, so the unique ability granted by the friendship is access to the private and protected members.

Inline functions in C++ are expanded at the place where they are called, rather than being invoked. Because of this, they cannot be virtual as the virtual mechanism relies on function calls.

A common memory leak scenario is when an exception is thrown before the memory allocated dynamically (usually with new) is deallocated. If the exception prevents a destructor or a delete statement from being reached, the memory is never released, resulting in a memory leak.

The primary purpose of enum (short for "enumeration") in C++ is to create user-defined data types where you can define a set of named integer constants. It provides a way to assign names to integral constants, which makes a program easier to read and maintain.

Encapsulation is achieved by bundling data (variables) and methods that operate on the data into a single unit (class) and restricting the direct access to some of the object's components. In C++, this is implemented by declaring variables as private and providing public methods (API) to access and manipulate them.

The bitwise OR operation works by comparing each bit position of the two numbers. If at least one bit is set (1) in a given position in either of the numbers, the resulting bit will be set. For 1101 OR 1010, the result is 1111.

Passing parameters by reference allows for direct access to the original memory location, eliminating the need for copying data. This reduces memory overhead and can enhance the performance of the program. While options 2 and 3 can also be benefits of passing by reference, the primary advantage is the reduction of memory usage.