Read the following Assertion and Reason and choose the correct option. Assertion: Salmonella typhi primarily causes respiratory infections in humans. Reason: Salmonella typhi bacteria enter the small intestine through contaminated food and water and can spread to other organs through the blood.

Step-by-step solution

A wide range of organisms belonging to bacteria, viruses, fungi, protozoans, helminths, etc., could cause diseases in man. Such disease- causing organisms are called pathogens. Most parasites are therefore pathogens as they cause harm to the host by living in (or on) them. The pathogens can enter our body by various means, multiply and interfere with normal vital activities, resulting in morphological and functional damage. Pathogens have to adapt to life within the environment of the host. For example, the pathoge