Identify reagent used for preparation of benzophenone from benzonitrile?

Identify reagent used for preparation of benzophenone from benzonitrile?
  1. $\mathrm{C}_6 \mathrm{H}_5 \mathrm{MgBr}$
  2. $\mathrm{CH}_3 \mathrm{MgCl}$ (in dry ether)
  3. $\left(\mathrm{CH}_3\right)_2 \mathrm{Cd}$
  4. $\mathrm{AlH}(\mathrm{i}-\mathrm{Bu})_2$

Asked in: MHT CET 2024 (11 May Shift 1)

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