Answer:
Option A
Explanation:
An equilateral triangle's sides are equal to each other, and all their angles are equal.
The best option is A.
What makes the other answers wrong:
All angles in a equilateral triangle are 60° each. They are not obtuse.
All three angles of a equilateral triangle are congruent. Again, they all measure 60° each.
All sides of a equilateral triangle are congruent.