Let a and $\mathrm{b} \in \mathrm{R}$ such that $0<\mathrm{a}<1,0<\mathrm{b}<1$. The values of $\mathrm{a}$ and $\mathrm{b}$ such that the complex numbers $\mathrm{z}_{1}=-\mathrm{a}+\mathrm{i}, \mathrm{z}_{2}=-1$ $+\mathrm{bi}$ and $\mathrm{z}_{\mathrm{a}}=0$ form an equilateral triangle are
(a) $a=b=2-\sqrt{3}$
(b) $a=2-\sqrt{3}, b=2+\sqrt{3}$
(c) $a=\sqrt{3}, b=-\sqrt{3}$
(d) $2,2 \sqrt{3}$