Bacterial cell division mainly by

✅Explanation: Binary fission is the primary mode of reproduction in bacteria. In this process, the bacterial cell duplicates its DNA and then divides into two identical daughter cells.

📌 Other Options Explanations:
-(b) Fragmentation: Fragmentation is a form of asexual reproduction where an organism breaks into fragments, each of which develops into a new individual. While some filamentous bacteria might exhibit fragmentation, it's not the main method of cell division for most bacteria.
-(c) Budding: Budding is a form of asexual reproduction where a new organism develops from an outgrowth or bud on the parent organism. It's common in yeasts (which are fungi) and some other organisms, but not the primary method in bacteria.  

🔑Key Points:
-Reproduction is the biological process in which the organism gives rise to young ones or offsprings similar to itself.
-It is responsible for the continuity of species generation after generation.

✏️Reproduction is mainly divided into two types:
-Sexual reproduction: 
-Involves the formation of the male and female gametes, either by the same individual or by different individuals of the opposite sex.
-These gametes fuse to form the zygote which develops to form the new organism.
-It is an elaborate, complex, and slow process as compared to asexual reproduction. (E.g. Mammals).
-The offsprings show characteristics of both male and female parents and show variation.

•        2. Asexual reproduction:
-The reproduction in which an offspring is produced by a single parent without the fusion of gametes is called asexual reproduction. (E.g. Amoeba, Hydra)
-The offsprings are exact replica of their parents and genetically identical.
– Asexual reproduction is of many types: Sporulation, Fission, Fragmentation. Budding, Plasmotomy, vegetative propagation, Apomixis & Parthenogenesis

• Binary Fission:
-It is asexual reproduction by a separation of the body into two new bodies.
-Under this, an organism duplicates its genetic material, and then divides into two parts (cytokinesis), with each new organism receiving one copy of DNA.
-Binary fission is seen in Single-celled organisms like protozoa 

• On the basis of the plane of division binary fission in protozoa is of the following types:
-Irregular Binary fission: This type of binary fission is seen in protozoans with irregular body forms. Here the body divides into two parts without any defined plane of fission. Eg – Amoeba
-Longitudinal binary fission: This type of binary fission is seen in protozoans belonging to the class Mastigophora. Here the fission occurs in a plane parallel to the longitudinal axis of the body of the organism. Eg – Euglena, Vorticella
-Transverse binary fission: This type of binary fission is seen in ciliated protozoans. Here the fission occurs in a plane right angle to the of the body of the organism. Eg – Paramecium
-Oblique Binary fission – This type of binary fission is seen in protozoans such as dinoflagellates. Here the fission occurs in a plane oblique to the body of the organism. Eg – Ceratium