In the Waterfall methodology, the phases flow sequentially:

Requirements → 2. Analysis → 3. Design → 4. Development → 5. Testing → 6. Implementation → 7. Maintenance.

The Testing phase comes immediately before Implementation, where the system is validated, bugs are fixed, and readiness is confirmed before deployment.

Option A: Analysis occurs much earlier in the process.

Option C: Development precedes testing, not implementation.

Option D: Maintenance comes after implementation.

Thus, the correct phase immediately before implementation is Testing.