In order for a triangle to be rotated in a symmetry that involves each rotation to matching vertices of the triangle, involves several of the options given in the list:
* All sides have the same length (we are dealing with an equilateral triangle)
* All angles ofthe triangle have the same measure (60 degrees each angle)
* A rotation of 60 degrees will map the traingle to itself (typical for a case of equilateral triangle)
* A rotation of 120 degrees will map the triangle with itself. (also in agreement with the answer immediately above, since 120 degree rotetion is the same as two consecutive 60 degree rotations)