The least possible Venn diagram for the given statements is as follow,
Conclusions: I. All wolfs are jackals → True (It is clear from the Venn diagram as "All wolfs are dogs and all dogs are jackals" so the all wolfs are jackals) II. All jackals are wolfs → False (It is not possible from the Venn diagram as "All wolf are dogs and all dogs are jackals" so the all jackals are not wolfs) Hence, "Only conclusion I follows" is the correct answer