Which pathogen is responsible for typhoid?

Symptoms of shigellosis,a diarrhoeal disease,are:

Assertion: $Escherichia$ $coli$,$Shigella$ $sp.$ and $Salmonella$ $sp.$ are all responsible for diarrhoeal diseases.
Reason: Dehydration is common to all types of diarrhoeal diseases and adequate supply of fluids and electrolytes should be ensured.

Meningitis,a disease responsible for the inflammation of the protective membranes covering the brain and spinal cord,is caused by:

What is the shape of $Salmonella$ $typhi$?

Which disease is caused by the bacterium $Salmonella$ $typhi$?