本人五月份去意大利做博士后，至少呆一年左右。最近需要办签证。那边说让办study visa，但是没说具体是哪一种。只是给了四个选项（如下）。没太理解这几种的区别是什么呢。听说不同类型办理难度也不一样。我想找一个办理手续相对简单的，并且能在留学期间去欧洲其他国家玩就行了。应该选哪一种啊？谢谢！

1.SINGLE ENTRY maximum 90 days stay SCHENGEN STUDY VISA (type C): On this Visa, youcan enter Italy and the other Schengen countries but only once.

2.MULTIPLE ENTRY maximum 90 days stay SCHENGEN STUDY VISA (type C): This Visa allowsyou to travel in and out of Italy, you can therefore visit any other country and re-enter Italy.

3.SINGLE ENTRY more than 90 days stay ITALIAN LONG-TERM STUDY VISA (type D): On thisVisa, you can travel from Italy only within the Schengen Area during the first 90 days of yourvisit, later, once you hold an Italian Permit of Stay (see below) you will be able to travel freely.

4.MULTIPLE ENTRY more than 90 days stay ITALIAN LONG-TERM STUDY VISA (type D): ThisVisa permits you to travel in and out of Italy and the other Schengen countries during the first90 days of your visit, later you will still be able to do it but only with your Permit of stay (seebelow).