Compare stability of the given carbocation
The question is pretty easy though the INDUCTIVE and MESOMARIC effects are same but there is a diffrence in the HYPERCONJUGATIVE Effect as in HYPERCONJUGATIVE Effect the bond between $C-H$ breaks to provide stability thus any change in bond energy of the bond to be broken changes the strength of effect.

Now as the bond strength of $C-T$ bond if highest hence the HYPERCONJUGATIVE Effect of $\ce{CT3}$ decreases and hence the carbocation is least stable.And $\ce{CH3}$ is most stable

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