One internode long modified stem capable of photosynthesis
A specialised reproductive shoot
Flattened green stem of unlimited growth
A perennial fleshy underground stem
The correct option is A One internode long modified stem capable of photosynthesis -Cladode: Phylloclade usually having one or two internodes long & succulent is called cladode. It is a special stem modification. Ex- Asparagus, and Ruscus.
-While the Phylloclade is green photosynthetic flattened or rounded succulent stem with leaves either feebly developed or modified into spines. Ex- Opuntia, Euphorbia and Cactus.
So, the correct answer is 'Option A- One internode long modifies stem capable of photosynthesis'.