Bacteriophages are viruses that infect bacteria. They are not viruses that infect animals (Option 1) or bacteria that infect plants (Option 3). Bacteriophages specifically target and infect bacteria, using them as hosts to replicate and reproduce.

Bacteriophages have a specific structure that allows them to attach to and penetrate the bacterial cell wall. Once inside the bacterial cell, the bacteriophage takes control and uses the cell`s machinery to replicate its own genetic material. This leads to the production of multiple copies of the bacteriophage, which eventually causes the bacterial cell to burst and release the newly formed bacteriophages.

Bacteriophages are considered beneficial in certain applications, such as in the field of medicine. They can be used to treat bacterial infections by specifically targeting the harmful bacteria while leaving the beneficial bacteria unharmed. This makes them a potential alternative to antibiotics, especially in cases where antibiotic resistance is a concern.

Therefore, the correct answer is Option 2: Bacteriophages are viruses that infect bacteria.