In C++, which of the following function causes the full definition of the function to be inserted in each place when it gets called?

In C++, the function that causes the full definition of the function to be inserted in each place when it gets called is known as an inline function.

Explanation:

1. Inline Functions: When a function is declared as inline, the compiler attempts to replace each call to the function with the function's body itself rather than using the standard function call mechanism. This can help in optimizing execution speed, especially for small, frequently called functions.

2. When Used: The inline keyword is a suggestion to the compiler to perform this optimization, but it is not guaranteed. Factors that might prevent this optimization include larger function sizes and recursive functions.

3. Syntax Example:

   inline int add(int a, int b) {
       return a + b;
   }
   

4. Performance Considerations: While inline functions can enhance performance by eliminating the overhead of function calls, excessive use can lead to increased binary size, as the function's body gets copied at each invocation site.

In summary, inline functions are the mechanism in C++ that causes the full function definition to be inserted at each point of call.