The correct combination is (4) (B), (E) and (F).

Evaluating each statement

• (A) Agrobacterium transfers a part of its chromosome into plant cell – False
  T‑DNA is located on the Ti/Ri plasmid, not on the bacterial chromosome; it is the plasmid segment that is transferred to plant cells, not chromosomal DNA.

• (B) Agrobacterium transfers a part of one of its plasmid DNA into plant cell – True
  During infection, a defined segment of the Ti (or Ri) plasmid (T‑DNA) is processed and delivered into the plant genome, so this statement is correct.

• (C) All the virulence genes of Agrobacterium are inducible – False
  Many vir genes are induced by plant signals via VirA/VirG, but not all virulence genes are purely inducible; some show basal or constitutive expression or complex regulation.

• (D) All the virulence gene products are functional only inside the bacterial cells – False
  Several vir proteins, such as VirE2 and VirF, are exported into the plant cell and function there (DNA coating, nuclear import, proteasomal uncoating), so this statement is incorrect.

• (E) Some of the virulence genes of Agrobacterium are inducible – True
  vir genes (virA, virB, virC, virD, virE, virG, etc.) are induced by acetosyringone and sugars via the VirA/VirG two‑component system, so “some … are inducible” is accurate.

• (F) Some virulence gene products are functional both in bacterial and plant cells – True
  Proteins like VirD2 act in the bacterium (T‑strand formation) and remain attached to T‑DNA in the plant, helping nuclear targeting; similarly, VirE2 is exported and functions in the plant, while being produced and partly processed in the bacterium.

Option-wise assessment

• (1) (A), (C) and (D) – All three are false.

• (2) (B), (D) and (E) – B and E are true, but D is false.

• (3) (C), (D) and (E) – C and D are false; only E is true.

• (4) (B), (E) and (F) – All three (B, E, F) correctly describe T‑DNA origin, inducible vir genes, and dual bacterial–plant functions of some vir proteins, so this is the correct choice.

SEO‑oriented introduction (for article use)

In Agrobacterium–plant interactions, the bacterium transfers a defined T‑DNA segment from its Ti plasmid, not from its chromosome, and several vir genes are inducible by plant‑released signals, leading to expression of virulence proteins. Some of these vir proteins, such as VirD2 and VirE2, are active in the bacterium during T‑strand formation and then continue to function inside the plant cell, so the true combination of statements is (B), (E) and (F).