Step 1: Use subshell capacity:
An s subshell holds 2 electrons and a p subshell holds 6. Argon fills all of 1s, 2s, 2p, 3s and 3p.
Step 2: Count subshells of each type:
Argon has 3 filled s subshells (1s, 2s, 3s) and 2 filled p subshells (2p, 3p).
Step 3: Multiply by capacity:
s electrons: $3 \times 2 = 6$. p electrons: $2 \times 6 = 12$.
Step 4: Cross-check:
The d subshell is empty in argon, so $6 + 12 = 18$ matches the atomic number. Only option C gives 6 and 12.
Final Answer:
Counting subshell by subshell gives 6 s electrons and 12 p electrons.
\[ \boxed{\text{(C) }6\ \text{and}\ 12} \]