Read the given question and decide which of the following statements is/are sufficient to answer the question.
Question:
There are five Oil Refining companies in India, namely A, B, C, D and E. Production of which of these companies is the highest?
Statements:
I. Production of Company B is more than that of Company A but not more than that of Company E.
II. Production of Company C is more than that of Company B but not as much as that of Company D.
III. Production of Company E is not as much as that of Company D.

There are five Oil Refining companies in India, namely A, B, C, D and E. 

According to given information:​

Statements:
Statement I: Production of Company B is more than that of Company A but not more than that of Company E.

E>B>A

Statement I alone not sufficient.
​Statement II: Production of Company C is more than that of Company B but not as much as that of Company D.

D>C>B

Statement II alone not sufficient.
​Statement III: Production of Company E is not as much as that of Company D.​​

D>E

Statement III alone not sufficient.

D>E/C>B>A

So, D company is the highest.

So, All the statements, I, II and III together, are sufficient.

Thus, the correct answer is (d).