Chromosomes are thread-like structures found in the nucleus of cells that contain genetic information in the form of DNA. They play a crucial role in the transmission of genetic material from one generation to the next. The number of chromosomes present in a cell can vary among different species.

In the case of onion root tips, these are actively growing regions of the plant where cell division takes place. To determine the number of chromosomes in each cell of the onion root tip, we need to consider the process of cell division known as mitosis.

Mitosis is a type of cell division that results in the production of two identical daughter cells, each containing the same number of chromosomes as the parent cell. During mitosis, the chromosomes condense and become visible under a microscope.

The number of chromosomes in a cell can be determined by counting the visible chromosomes during mitosis. This is typically done by preparing a slide of the onion root tip cells and staining them to enhance the visibility of the chromosomes.

The correct answer to the question is option 'C', which states that there are 16 chromosomes present in each cell of the onion root tip. This means that during mitosis, the chromosomes condense and become visible as 16 distinct structures.

It is important to note that the number of chromosomes can vary among different species. In the case of onions, they have a diploid number of 16 chromosomes, meaning that each cell contains two sets of chromosomes. This is denoted as 2n=16, where 'n' represents the number of unique chromosomes.

In conclusion, the onion root tip cells contain 16 chromosomes in each cell. This is determined by counting the visible chromosomes during mitosis, where the chromosomes condense and become visible as distinct structures.