The higher stabilities of $tert$-butyl cation over isopropyl cation and $trans-2-butene$ over propene,respectively,are due to orbital interactions involving

• A
  $\sigma \rightarrow \pi$ and $\sigma \rightarrow \pi^{*}$
• B
  $\sigma \rightarrow \text{vacant } p$ and $\sigma \rightarrow \pi$
• C
  $\sigma \rightarrow \sigma^{*}$ and $\sigma \rightarrow \pi$
• D
  $\sigma \rightarrow \text{vacant } p$ and $\sigma \rightarrow \pi^{*}$