The California legislature passed a law to make Amazon collect tax for products sold to California residents because the residents weren't paying...

The clue to the correct answer is in the question.  It says that Amazon has to collect tax on items sold to California residents.  A tax that is levied on items that are sold to people is a sales tax.

The law mentioned in this question was passed in 2012.  Before that, there had been a great deal of controversy over whether Amazon (and other online sellers) should have to collect sales taxes when they sold items to people outside of the state in which Amazon was physically located.  At first, Amazon did not have to do so.  Now, more states require this.

The only other answer that would make any sense is “excise tax.”  However, excise taxes are collected only on certain specific items.  For example, there is an excise tax on cigarettes.  Excise taxes do not apply to all items that are sold the way that sales taxes typically do.

The law that California passed was a law that requires Amazon to collect sales tax on the items it sells to people in California.