The least possible Venn diagram according to statements given :
Conclusions : I. No bike is a van → False (There is no direct relation between bike and van given, so, this statement is not absolutely true. It is just a possibility).
II. No auto is a van → False (Some vans are autos which implies some vans are also autos, so, this statement is incorrect).
III. Some bikes are vans → False (There is no direct relation between bike and van given, so, this statement is not absolutely true. It is just a possibility).
Here, Conclusion (i) and conclusion (ii) are forming a complementary pair.
Only one case is possible at a time.
So, either conclusion (i) can follow or conclusion (ii) at a time.
Hence, the correct answer is "Either conclusions I or III follows".