Where does the helix ( r(t) = ⟨ cos(π t), sin(π t), t ⟩ ) intersect the paraboloid ( z = x² y² )?

a. ( z = cos²(π t) sin²(π t) )
b. ( z = sin²(π t) cos²(π t) )
c. ( z = π² )
d. ( z = sin(π t) cos(π t) )