The magnitude of crystal field stabilization energy (CFSE or Δt ) in tetrahedral complexes is considerably less than in the octahedral field. Because

There are only four ligands instead of six on the ligand field is only 2/3 the size hence the Δt is only 2/3 the size

The direction of the orbitals does not coincide with the direction of the ligands. This reduces the crystal field stabilization energy (Δt) by further 2/3

Both points (a) and (b) are correct

Both points (a) and (b) are wrong