Imagine yourself to be a microbial pathogen, tell us the reason for your choice, and describe in detail the structures you would like to have in order to live in the habitat of choosing and the factors needed to cause infection of a specific organ in humans.
Being a microbial pathogen opens up many doors. Since bacteria can survive just about anywhere, you can infect plants, animals, fungi, or even other bacteria. The directions suggest humans, so go with that. Things to consider here what disease are you looking to cause. Examples include types of food poisoning (salmonella, etc.), a sexually transmitted disease (that could be fun!) like Chlamydia, or something like strep throat. Once you have selected the disease, investigate the vector, or how it is ...
This responses describes the options available when selecting a microbial pathogen. It discusses different examples of pathogens along with their living conditions and shapes. References are provided.