Seven books P, Q, R, S, T, U and V are placed side by side. R, Q and T have blue covers and other books have red covers. Only S and U are new books and the rest are old. P, R and S are law reports; the rest are Gazetteers. Books of old Gazetteers with blue covers are

The correct option is Q and T.

To find the books that fulfill all the given criteria, let us systematically analyze the properties of each of the seven books: P, Q, R, S, T, U, and V based on the information provided in the question.

1. Cover Color:

- Blue covers: R, Q, T

- Red covers: P, S, U, V

2. Age/Condition:

- New books: S, U

- Old books: P, Q, R, T, V

3. Category/Type:

- Law reports: P, R, S

- Gazetteers: Q, T, U, V

Now, we need to find the books that are old Gazetteers with blue covers. This means the required books must satisfy three conditions simultaneously:

1. They must be Old (P, Q, R, T, V)

2. They must be Gazetteers (Q, T, U, V)

3. They must have Blue covers (R, Q, T)

Let us check the common elements (intersection) of these three sets:

- Old Gazetteers: {P, Q, R, T, V} ∩ {Q, T, U, V} = {Q, T, V}

- Old Gazetteers with Blue covers: {Q, T, V} ∩ {R, Q, T} = {Q, T}

Therefore, the books of old Gazetteers with blue covers are Q and T.