Which of the following is true about tracheids and vessels
1. Tracheids are multicellular with narrow lumen
2. Tracheids are unicellular with wide lumen
3. Vessels are multicellular with wide lumen
4. Vessels are unicellular with narrow lumen

Common feature in vessel elements and sieve tube elements is

The annular and spirally thickened conducting elements generally develop in the protoxylem when the root or stem is