Concept:
Cladode is a modified stem performing photosynthesis.
Step 1:
Cladode is green flattened stem modified for photosynthesis.
Step 2:
Ruscus possesses cladodes.
Step 3:
• Berberis has spines
• Phoenix has pinnate leaves
• Argemone lacks cladodes
Step 4:
Hence cladode is found in:
\[
\boxed{\text{Ruscus}}
\]
\[
\boxed{\text{Correct Option = (2)}}
\]