  We investigate a (super-)renormalizable and ghost-free theory of gravity,
showing that under a natural (exponential) ansatz of the form factor and a
suitable truncation it can give rise to the Starobinsky inflationary theory in
cosmological frameworks, and thus offering a theoretical justification of its
origin. We study the corresponding inflationary evolution and we examine the
generation of curvature perturbations, adapting the $f(R)$-like equations in a
symmetry-reduced FLRW metric. Furthermore, we analyze how the ultraviolet
regime of a simply renormalizable and unitary theory of gravity is also
compatible with the Starobinsky action, and hence we show that such a theory
could account for an inflationary phase of the Universe in the ultraviolet
regime.
