Heterosis can be fully exploited in the form of:

Correct option is C

✅ (c) Hybrids: • Heterosis or hybrid vigor is maximized in F1 hybrids. • These hybrids show better growth, yield, and resistance. • Common in crops like maize, cotton, rice.
❌ (a) Synthesus: • Likely meant "synthetics", not ideal for full heterosis exploitation.
❌ (b) Composites: • Used in open-pollinated crops, not as effective in expressing heterosis.
❌ (d) Multilines: • Mixtures of genotypes, not designed for heterosis exploitation.