To solve this question, the user needs to have knowledge of C++ programming language and the concept of member functions.

The implicit pointer that is passed as the first argument for nonstatic member functions in C++ is known as the 'this' pointer.

Option A: 'self' pointer is not a valid keyword in C++. Hence, this option is incorrect.

Option B: std::auto_ptr is a smart pointer that is used for automatic memory management in C++. However, it is not passed as the first argument for nonstatic member functions. Hence, this option is incorrect.

Option C: 'Myself' pointer is not a valid keyword in C++. Hence, this option is incorrect.

Option D: 'this' pointer is a pointer that points to the object for which the member function is called. It is passed as a hidden argument to non-static member functions. Hence, this option is correct.

Therefore, the answer is: D. 'this' pointer.