Please, help-me with this Linear Algebra question

Question

If T:R4→R4 is an linear transformation and pT(t) a characteristic polynomial of T, which of these options T is diagonalizable

a) pT(t) = t^4 - 1

b) pT(t) = t^3(t + 2)

c) pT(t) = t^2(t^2 - 1)

d) pT(t) = t^2(t^2 - 2t + 1)

Answer 1

Can you rewrite the question? Like this it is not clear what the question is.