Step 1: Understanding black rot in cabbage.
Black rot is a serious bacterial disease of crucifers caused by Xanthomonas campestris pv. campestris. It reduces head quality and yield drastically.
Step 2: Resistant variety.
- Pusa Mukta is a cabbage variety specifically bred for resistance to black rot disease.
- Pusa Ageti and Pusa Drum Head are popular varieties but not resistant to black rot.
- September is another non-resistant variety.
Step 3: Conclusion.
Hence, the black rot resistant variety of cabbage is Pusa Mukta.
Final Answer: \[ \boxed{\text{Pusa Mukta is resistant to black rot disease.}} \]