Gossypium arboreum species of cotton are found resistant against disease:

Correct option is C

Gossypium arboreum, also known as desi cotton, is naturally more resistant to several diseases compared to other cotton species like Gossypium hirsutum (American cotton). One of the notable resistances exhibited by G. arboreum is against bacterial leaf blight (BLB).

Detailed Option Analysis:

• (A) Root rot
  G. arboreum does not have significant inherent resistance to root rot pathogens such as Rhizoctonia solani or Macrophomina phaseolina. These fungal diseases affect multiple cotton species.
• (B) Wilt
  While some resistance exists, especially against Fusarium wilt, it is not the most prominent or highest-priority trait of G. arboreum when compared to BLB resistance.
• (C) Bacterial leaf blight
  G. arboreum shows natural resistance to Xanthomonas citri pv. malvacearum, the pathogen causing BLB. This trait makes it an important genetic resource for breeding resistant varieties.
• (D) Leaf curl
  Cotton leaf curl disease (CLCuD) caused by a begomovirus is still a concern in G. arboreum. It is not fully immune, though it may show partial tolerance in certain genotypes.