What is the major product of the reaction between 4-chlorobut-1-ene?
In solvolysis of simple primary cyclopropylmethyl systems the rate is
  enhanced because of participation by the $\sigma $ bonds of the ring. The ion
  that forms initially is an unrearranged cyclopropylmethyl cation that is
  symmetrically stabilized, that is, both the 2,3 and 2,4 $\sigma $ bonds help
  stabilize the positive charge(page 464 ,JerryMarch ,Advanced Organic Chemistry
  Reactions, Mechanisms,and Structure,Sixth Edition).


The reaction of various cyclopropylmethyl systems are given below. 



In the question 4-chlorobut-1-ene  (1) undergoes rearrangement as shown in the scheme 3 and scheme 4 to give 1a, 1b and 1c.Assuming solvolysis with acetic acid ,1a, 1b and 1c would give 2, 3 and 4.