The most stable vanadium species in aqueous medium is (1) $\mathrm{[V(H_2O)_5(OH)]^{+2}}$ (2) $\mathrm{[VO(H_2O)_5]^{+2}}$ (3) $\mathrm{[VO(H_2O)_5]^{+}}$ (4) $\mathrm{[V(H_2O)_4(OH)_2]^{+2}}$
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.
Explanation
In aqueous medium, the most stable vanadium species is hydrated vanadyl ion [VO]+2 i.e [VO(H2O)5]+2
Explanation as extracted from the printed page; notation may be imperfect.