Mastering C++: A Comprehensive Quiz Based on 'Thinking in C++

Option A, pointer arithmetic, is a core feature of the C language and is commonly used by experienced C programmers. This makes it unlikely to be unfamiliar to them. Option B, struct definition, is also a fundamental feature of C and is well-known by experienced C programmers. Option D, macros and preprocessors, are widely used in C and are likely to be familiar to experienced C programmers. Therefore, C++ features interspersed in C syntax is the most likely answer as it involves concepts from a different language, making it unfamiliar even to experienced C programmers.