**Core Concept**
The question tests the understanding of different levels of health workers in a healthcare system. Grass-root level workers are those who provide primary healthcare services directly to the community, often in rural or underserved areas.

**Why the Correct Answer is Right**
Grass-root level workers typically include health assistants, auxiliary nurse midwives, and community health workers. They play a crucial role in providing basic health care services, health education, and disease prevention. These workers are usually the first point of contact for patients in rural or underserved areas.

**Why Each Wrong Option is Incorrect**
**Option A:** Health workers involved in training and supervision, such as medical educators or trainers, are not typically considered grass-root level workers. They work at a higher level, focusing on capacity building and skill development for other health workers.
**Option B:** Medical officers, including doctors and specialists, are also not grass-root level workers. They provide secondary and tertiary care services, often in hospitals or clinics.
**Option C:** This option is not provided, so we will skip it.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize the different levels of health workers and their roles in the healthcare system. Grass-root level workers are critical for providing accessible and equitable healthcare services, especially in resource-constrained settings.

**Correct Answer: A. Health workers involved in training and supervision are not typically considered grass-root level workers.**