## Core Concept
The minimum infective dose (MID) is the smallest number of microorganisms required to cause infection in a host. For *Shigella*, a gram-negative bacterium causing shigellosis, this concept is crucial in understanding its pathogenicity and transmission dynamics.

## Why the Correct Answer is Right
The correct answer, , indicates that the minimum infective dose of *Shigella* is as low as 10-100 organisms. This low MID is a characteristic feature of *Shigella* species, contributing to their high infectivity. The bacteria's ability to survive passage through the stomach and establish infection in the intestines with such a small inoculum makes them highly pathogenic.

## Why Each Wrong Option is Incorrect
* **Option A:** - This option suggests a much higher MID, which does not align with the known high infectivity of *Shigella* at low doses.
* **Option B:** - Similar to option A, this dose is higher than the established MID for *Shigella*, making it incorrect.
* **Option D:** - This option suggests an even higher dose, which is not consistent with the low MID characteristic of *Shigella* infections.

## Clinical Pearl / High-Yield Fact
A key point to remember is that *Shigella* infections can spread through fecal-oral contamination, and given its low MID, even minor lapses in hygiene can lead to outbreaks. This is particularly concerning in crowded settings or areas with poor sanitation.

## Correct Answer: .