Organelle which is surrounded by double membrane is

Solution:

Among the given options:

1. Lysosomes are single membrane-bound organelles.

2. Polysomes (or polyribosomes) are aggregates of ribosomes attached to an mRNA molecule. Ribosomes themselves are non-membranous organelles.

3. Smooth endoplasmic reticulum is a single membrane-bound organelle.

4. Chloroplasts are double membrane-bound organelles, along with mitochondria and the nucleus. They are responsible for photosynthesis in plant cells.