Question

Let D = {(s, t) | s^2 + t^2 ≤ 1, s ≥ 0, t ≥ 0} and let x: D -> R^3 be defined as x(s, t) = (s, t, st). This question is related to:
a) Linear algebra
b) Geometry
c) Topology
d) Trigonometry