Consider the following morphological break-up of pfeifing produced by a simultaneous bilingual child. What phenomenon does this example indicate?

Step 1: Distinguish code-mixing vs. code-switching
- Code-mixing refers to inserting elements of one language into another at word or phrase level (e.g., Hinglish).
- Code-switching refers to shifting between languages based on context, discourse, or social setting.
Step 2: Analyze the example
Here, the child uses the German stem pfeife and attaches the English progressive morpheme -ing, creating the hybrid form pfeifing. This is not simple code-switching (contextual) or social code-mixing, but rather indicates that the child sees both languages as one integrated system of morphology.
Step 3: Theoretical support
In bilingual acquisition studies, simultaneous bilingual children often blend grammatical rules from both languages, suggesting a unitary linguistic system hypothesis.
\[
\boxed{\text{Answer: Understanding both languages as part of a single 'system' (C)}}
\]
Examine the given data. The value of X is ________ (in integer). 
Eight students (P, Q, R, S, T, U, V, and W) are playing musical chairs. The figure indicates their order of position at the start of the game. They play the game by moving forward in a circle in the clockwise direction.
After the 1st round, the 4th student behind P leaves the game.
After the 2nd round, the 5th student behind Q leaves the game.
After the 3rd round, the 3rd student behind V leaves the game.
After the 4th round, the 4th student behind U leaves the game.
Who all are left in the game after the 4th round?
