Which reaction shows artificial transmutation by $\mathrm{\alpha }$-bombardment?

• A

  ${ }_7^{14}\mathrm{N}{+}_2^4\mathrm{He}{⟶}_8^{17}\mathrm{O}{+}_1^1\mathrm{H}$

• B

  ${ }_{92}^{238}\mathrm{U}{⟶}_{90}^{234}\mathrm{Th}{+}_2^4\mathrm{He}$

• C

  ${ }_6^{14}\mathrm{C}{⟶}_7^{14}\mathrm{N}{+}_{-1}^0\mathrm{e}$

• D

  $H_1^2+H_1^{2 }\to H{e}_2^4$