1. Identify the reacting species

   Acidified potassium dichromate contains the dichromate ion, $\mathrm{Cr_2O_7^{2-}}$, in which chromium is in the oxidation state $+6$.

   Potassium iodide provides iodide ions, $\mathrm{I^-}$, which act as a reducing agent.

2. Determine what happens in acidic medium

   In acidic medium, dichromate is a strong oxidizing agent and gets reduced.

   The reduction half-reaction is: $\mathrm{Cr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2O}$

   So chromium goes from oxidation state $+6$ to $+3$.

3. Oxidation of iodide

   Iodide gets oxidized to iodine: $\mathrm{2I^- \rightarrow I_2 + 2e^-}$

   Multiplying by $3$ to balance electrons: $\mathrm{6I^- \rightarrow 3I_2 + 6e^-}$

4. Overall balanced reaction

   Adding the two half-reactions: $\mathrm{Cr_2O_7^{2-} + 14H^+ + 6I^- \rightarrow 2Cr^{3+} + 3I_2 + 7H_2O}$

5. Final oxidation state of chromium

   In the final product, chromium is present as $\mathrm{Cr^{3+}}$.

   Therefore, the oxidation state of chromium is: $\boxed{+3}$

6. Option check

   • A: $+3$ ✅ Correct
   • B: $+2$ ❌ Incorrect
   • C: $+6$ ❌ Incorrect
   • D: $+4$ ❌ Incorrect

Hence, the correct answer is A.