Step 1: Narrow down by the disease.
White rust in Brassica is caused by the pathogen Albugo candida, and breeders have specifically worked to develop resistant cultivars against it.
Step 2: Recall the named cultivars and what each was bred for.
Pusa gaurav and Pusa komal target different traits in Brassica breeding programmes, and Pusa Sawani is actually an okra variety, not Brassica.
Step 3: Match the resistant variety.
The cultivar specifically developed and recognised for resisting white rust in Brassica is Pusa swarnim.
Final answer: Option 3, Pusa swarnim.