What is the correct simplified (noble-gas) electron configuration of krypton (Kr)?

• A. [Ne] $3^s$$2^{}$ $3^p$$6^{}$ $4^s$$2^{}$ $3^d$${10}^{}$ $4^p$$6^{}$
• B. [Ar] $4^s$$2^3$ $3^d$${10}^{}$ $4^p$$6^{}$
• C. [Ar] $4^s$$2^{}$ $3^d$${10}^{}$ $4^p$$6^{}$
• D. [Kr] $5^s$$2^{}$

Answer: (C)