Step 1: Concept
Acylation of aromatic amines.
Step 2: Meaning
Benzenamine (aniline) reacts with ethanoic (acetic) anhydride to introduce an acetyl group ($CH_3CO-$) onto the nitrogen.
Step 3: Analysis
The reaction replaces a hydrogen atom on the $-NH_2$ group with an acetyl group, forming acetanilide, also known as N-phenylethanamide.
Step 4: Conclusion
Hence, the correct answer is N-phenylethanamide.
Final Answer: (C)