Answer: (A) Equilateral triangle
The arcs AB and BC have only B in common, so the remaining arc CA has measure
\[360^\circ - 120^\circ - 120^\circ = 120^\circ\]All three arcs are congruent, so the chords AB, BC, CA are congruent. Hence \(\triangle ABC\) is equilateral. (Each inscribed angle is \(\frac{1}{2} \times 120^\circ = 60^\circ\).)
An equilateral triangle is also isosceles, but the most precise type is equilateral.