Two statements are given, followed by three conclusions numbered I, II and III.
Assuming the statements to be true, even if they seem to be at variance with
commonly known facts, decide which of the conclusions logically follow(s) from the statements.
Statements:
All Birds are Sparrows.
All Sparrows are Reptiles.
Conclusions:
I. Some Reptiles are Birds.
II. All Reptiles are Sparrows.
III. All Birds are Reptiles.

As per the Statements given in question, we get the above Venn diagram,

Conclusion : 

1.  Some reptiles are birds. : True (clearly seen all birds are reptiles so, it follows.)

2.All Reptiles are Sparrows : False (All sparrows are reptiles but its vice-versa is not possible.)

3. All birds are reptiles : True (All birds are sparrows and all sparrows are reptiles.,so all birds are reptiles.)

Hence, Conclusion 1 and 3 follows, 

Hence, Option D is correct.