Correct carbocation stability order:

Step 1: Identifying Carbocation Type Carbocation stability is primarily determined by hyperconjugation and inductive effects from alkyl groups.

• $\ce{(CH3)_3\overset{+}{C}}$ ($3^\circ$)
• $\ce{(CH3)_2\overset{+}{C}H}$ ($2^\circ$)
• $\ce{CH_3\overset{+}{C}H_2}$ ($1^\circ$)
• $\ce{\overset{+}{C}H_3}$ (Methyl)

Step 2: Stability Order The order is Tertiary ($3^\circ$) > Secondary ($2^\circ$) > Primary ($1^\circ$) > Methyl.

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