Answer:
E1
Explanation:
A detailed mechanism of the reaction is shown in the image attached obtained from UCSB.
We can see from the mechanism that the reaction occurs via a carbocation intermediate. The transition state involves a carbcation and this is only typical of an E1 mechanism.
Furthermore, there is a 1,2-hydride shift which leads to the formation of the more stable tertiary carbocation. The products clearly indicate a rearrangement and points towards an ionic mechanism in operation.