How many of the following will not show tautomerism?

a) $C{H}_{3}C{H}_{2}C{H}_{2}C{H}_{2}N{O}_2$   b) ${\left(C{H}_3\right)}_{2}CH-C{H}_{2}N{O}_2$    c) $C{H}_3\underset{N{O}_2}{\underset{|}{CH}}-C{H}_{2}C{H}_3$  d) ${\left(C{H}_3\right)}_{3}C-NO$

d,f,g do not show tautomersim due to absence of alpha hydrogen. If the compound has no `alpha` hydrogen on a saturated carbon next to the keto group or CN or Nitro or oxime group then it cant show tautomerism.Aromatisation/hydrogen bonding is the driving force to convert keto form to enol form.