Step 1: Understanding the Concept: 
Development programmes can be broadly categorized. Area-based programmes focus on developing a specific geographical region (e.g., a drought-prone area, a hill area). Target-group programmes focus on improving the conditions of a specific section of the population (e.g., small farmers, landless laborers). 
Step 2: Detailed Explanation: 
Let's classify the given programmes: 
1. Command Area Development Programme: Focuses on improving water management in the 'command area' of an irrigation project. This is an area-based programme. 
2. Drought Prone Area Development Programme: Aims to mitigate the adverse effects of drought in identified arid and semi-arid regions. This is an area-based programme. 
3. Desert Development Programme: Focuses on controlling desertification and developing the economy of desert regions. This is an area-based programme. 
4. Small Farmers Development Agency (SFDA): This was established specifically to identify and assist small and marginal farmers with credit, inputs, and other services. Its focus is on a particular group of people, not a geographical area, making it a target-group programme. 
Step 3: Final Answer: 
The Small Farmers Development Agency is a target group development programme.