Match column-I (scientists) with column-II (discovery) and select the correct option.

Column-I	Column-II
A. Leeuwenhoek	I. First saw and described a living cell
B. Robert Brown	II. Presence of cell wall is unique to plant cells
C. Schleiden	III. Discovered the nucleus
D. Schwann	IV. All plants are composed of different kind of cells

Leeuwenhoek He is commonly known as the Father of Microbiology, and considered to be the first microbiologist. First saw and described a living cell.
Robert Brown was a Scottish botanist and palaeobotanist who made important contributions nucleus and cytoplasmic streaming.
Schleiden was a German botanist and co-founder of the cell theory, along with Theodor Schwann and Rudolf Virchow. He discovered that all plants are composed of different kind of cells.
Schwann - He discovered that presence of cell wall is unique to plant cells.