Which one of the following represents the hyperconjugation effect?

• A
  $CH_3-CH=CH_2 \rightarrow H^+ + CH_2=CH-CH_2^-$
• B
  $CH_2=CH-Cl: \rightarrow :CH_2-CH=Cl^+$
• C
  $CH_3-CH_2$ $\rightarrow NO_2$ $\rightarrow CH_3-\stackrel{\delta+}{CH_2}-\stackrel{\delta-}{NO_2}$
• D
  $CH_3-CH=CH_2 + H^+ \rightarrow CH_3-CH^+-CH_3$