Fill in the blank with an appropriate preposition given in alternatives below the sentence– ‘He has pasted the notice ……… the board.’

The correct answer is B) on the board. A notice is pasted on a surface, and a notice board is a flat surface. The preposition on shows contact with a surface, which is exactly the relation here.

• A (in the board): in signals enclosure, as in a box or a room. A board is not a container, so this is wrong.
• C (upon the board): Grammatically acceptable and more formal, but the idiomatic English for pasting or fixing something to a surface is on. In a single-answer exam, the idiomatic choice is B.
• D (at the board): at marks a point or location, such as standing at the board to write. It does not describe affixing something to it.

The core concept is the basic spatial trio: in (enclosed), on (surface contact), at (a point). Clear, precise English matters in Mains too, since drafting official notices and reports depends on this kind of accuracy.

Trap: Aspirants pick C because "upon" looks more formal, or A because they picture the board as a space. Choose the idiom, not the fancier word.