Membrane system considered to be extension of infolded plasma membrane is
A) Golgi complex
B) Plastids
C) Mitochondria
D) Endoplasmic reticulum

Hint: The main components of the endomembrane system are: endoplasmic reticulum, Golgi apparatus, vesicles, nuclear envelope and cell membrane.

Complete Answer:
1) Golgi body, also known as a Golgi apparatus or dictyosome, is a cell organelle which is responsible for processing and packaging of proteins
2) Plastids are double-membrane organelles which are present plants and algae. Plastids have functions of manufacturing and food storage. They contain pigments which are used in photosynthesis as well as are of different types because of pigments that can change the colour of the cell.
3) Mitochondria are double membrane-bound cell organelles (mitochondrion, singular) which are responsible for generating chemical energy needed to power the cell's biochemical reactions. The chemical energy which is produced by the mitochondria is stored in a molecule which is called adenosine triphosphate (ATP).
4) Endoplasmic reticulum (smooth and rough) is a network of interconnected flattened, membrane-enclosed sac-like structures which are distributed throughout the cytoplasm. It actually forms a continuous membrane system with the nuclear membrane and are the extensions of the infolded plasma membrane.

So, the correct answer is option (D) 'Endoplasmic reticulum'.

Note: The endomembrane system includes the lysosomes, vesicles, nuclear envelope, the ER and Golgi apparatus as well as the plasma membrane. The endomembrane system, however, never includes the membranes of chloroplasts or mitochondria but are thought to have evolved from the latter.