This question checks whether a superlative form is used correctly inside a sentence. The full sentence reads: 'A wise and experienced manager will assign a job to whom ever is best qualified.' It is split into four parts, and you have to find which part carries a grammar slip, or mark 'No error' if the sentence is clean.
The error sits in the fourth part, 'best qualified', because the superlative 'best' is left without its article. Adding 'the' gives the grammatically complete phrase 'the best qualified', so the correct choice is option (d).
Let's summarize:
So the answer is option (d), best qualified, since it drops the article that a superlative form needs.
If the price of a commodity increases by 25%, by what percentage should the consumption be reduced to keep the expenditure the same?