Which type of bacteria is known for forming pus and is arranged in curved lines?

The correct answer is associated with a type of bacteria that typically forms in chains. Streptococci are spherical, gram-positive bacteria known for their arrangement in curved or twisted chains. They can be involved in various infections and are noteworthy for their capability to produce pus, which is often associated with infections. This characteristic links them closely with conditions like strep throat and skin infections that result in pus formation.

In contrast, while staphylococci are also known to produce pus, they typically form clusters resembling grapes rather than strings. Bacilli refer to rod-shaped bacteria, and vibrio are comma-shaped or curved rods, which generally do not form pus in the same context as streptococci. Hence, the classification of streptococci accurately fits the description provided in the question.