Find an arc length parametrization of the line.

a) x(t)=1/√2 t, y(t)=1/√2 t, z(t)=1/√2 t
b) x(t)=2t, y(t)=3t, z(t)=4t
c) x(t)=t, y(t)=2t, z(t)=3t
d) x(t)=1/3t, y(t)=1/3t, z(t)=1/3t