c. Which of the fallowing are valid statistical models

Question

a) R{N(θ,1)} θ>10
b) (θ,inf) {t->e^ (θ-t) 1(t> θ) } θ>0
c)([0,inf], {N(u,σ^2})u> σ^2
d)([0,inf]), {x->e^ θx 1>(x>0) θ >0}