Equation of a line which passes through a point with position vector c, parallel to the plane r.n = 1 and perpendicular to the line r = a + tb is
→ → → → →
a. r = c + λ(c − a) × n
→ → → →
b. r = c + λ(a × n)
→ → → →
c. r = c + λ(b × n)
→ → → →→
d. r = c + λ(b × n)a