Select the correct alternative for blank (87).

Concept: In a meaning-based cloze blank, grammar cannot settle the answer, because each alternative offered forms a perfectly grammatical noun phrase after "searching for the ___", so the syntax leaves all four of them open. Such a blank is decided by sense alone: the word chosen must name whatever the surrounding sentences logically require, and the sharpest evidence is the consequence the passage reports and the setting it establishes.

Application: The sentence is a cleft — "It was, while searching for the ___ that, by mistake she upset the inkpot." The cleft ties the accident to the act of searching, so the search must be a hands-on, physical rummage that brings her within reach of the inkpot. The remaining blanks fix the setting as an ordinary domestic one: Mother rebukes her mildly and calls the result "a royal mess", that is, ink spilt across a work surface. The blank therefore needs the name of a small tangible article that a person hunts for among the things lying on a writing desk, and that naturally shares that desk with an inkpot. Glue answers to that description, so blank (87) takes glue.

Cross-check: Weigh each alternative against the two demands the passage makes on the word — that it name a physical article, and that hunting for it can end with an inkpot knocked over.

• clue — a piece of evidence pointing towards the solution of a mystery. Hunting for a clue is an act of reasoning about evidence, and the passage sets up no mystery, no puzzle and no investigation anywhere in its four blanks.

• story — a connected account of events. A person composes, tells or reads a story; the passage describes someone rummaging beside an inkpot, which is not how a story is come by.

• plot — the arrangement of incidents inside a narrative. Like a story it is worked out in the mind rather than found on a desk, so it cannot explain a physical accident with an inkpot.

• glue — a sticky preparation kept with pens, paper and ink. Reaching about a cluttered desk for it is exactly the kind of search that ends with an inkpot tipped over, and it belongs to the same domestic scene as Mother and the spilt ink.

So the completed line reads: "It was, while searching for the glue that, by mistake she upset the inkpot."