Step 1: Recall sector definitions.
Primary = agriculture, fishing, forestry, mining; Secondary = manufacturing; Tertiary = services.
Step 2: Map to rural reality.
Rural livelihoods in India largely depend on agriculture and allied activities → the primary sector.
Step 3: Eliminate distractors.
Secondary and tertiary sectors are present but not predominant in most rural regions.
Step 4: Conclusion.
Hence, (A) Primary.