Match List-I with List-II (Electronic effects):

Step 1: Matching Effects to Mechanisms

• (A) Aniline resonance: Electrons move into the ring. This is $+R$ effect. (A-IV)
• (B) Cyclohexene + $\ce{H^+}$: Double bond electrons migrate to the attacking reagent ($\ce{H^+}$). This is $+E$ effect. (B-III)
• (C) Cyclohexene + $\ce{CN^-}$: Double bond electrons move away from the attacking reagent ($\ce{CN^-}$). This is $-E$ effect. (C-I)
• (D) Nitrobenzene resonance: Electrons move toward the substituent. This is $-R$ effect. (D-II)

Step 2: Correct Match (A)-(IV), (B)-(III), (C)-(I), (D)-(II).

$\boxed{\text{Answer: (a)}}$