On the unit circle, where 0 is less than theta comma theta is less than or equal to 2 pi , when is tangent theta undefined?

Tangent is defined as sin θ / cos θ, so it is undefined when cos θ = 0. On the unit circle, this occurs at θ = π/2 and θ = 3π/2 in the given interval. Therefore, the correct choice is B.

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