Which of the following is the correct order of crystal field splitting strength for ligands based on the donor atom?

According to crystal field theory, the correct order of ligands with respect to their decreasing order of field strength is

Which of the following ligands will cause the smallest crystal field splitting?

Given below are two statements $:$
Statement $(I) :$ In octahedral complexes,when $\Delta_{o} < P$ high spin complexes are formed. When $\Delta_{o} > P$ low spin complexes are formed.
Statement $(II) :$ In tetrahedral complexes because of $\Delta_{t} < P$,low spin complexes are rarely formed.
In the light of the above statements,choose the most appropriate answer from the options given below $:$

For a $d^{4}$ metal ion in an octahedral field,the correct electronic configuration is:

Why are low spin tetrahedral complexes not formed?