The correct answer is option 4, Robert Hooke. Robert Hooke was an English scientist who, in 1665, published a book called "Micrographia" in which he described his observations using a compound microscope. In this book, he reported his observations of a thin slice of cork that he had examined under his crude microscope. He described the structures he saw as "cells" because they reminded him of the small rooms monks lived in, known as cells.

It is important to note that although Robert Hooke was the first to observe cells in cork, he did not discover cells as a general concept. The use of the term "cell" to describe these structures was popularized by Hooke, but the actual discovery of cells as the basic structural and functional units of all living organisms was made by later scientists.

Option 1, August Weismann, is an incorrect answer as he was a biologist who made significant contributions to the theory of evolution through his research on inheritance.

Option 2, Louis Pasteur, is also an incorrect answer as he was a chemist and microbiologist who made important discoveries in the area of germ theory of disease and pasteurization.

Option 3, Robert Brown, is an incorrect answer as he was a Scottish botan