Which of the following indicatrix can be obtained if 2v 180° ? uniaxial positive uniaxial negative biaxial positive biaxial rnegative

Uniaxial negative as 2v is either 0 or 180 in uniaxial mineral.

I think logic behind 2V 180° is to having only one optic axis which is only possible in Uniaxial minerals. Let's 2Va+2Vb = 180° ===> if one 2Va =0 then only one remaining 2V...