The error lies in part B of the sentence that the preposition ‘of’ must follow the verb ‘thought’ to make the sentence correct. To express clearly what was being thought ‘of’ is needed to specify the action.

The phrase is 'frighten someone off'. The word 'fright' is incorrect here. The noun 'elephants' must be written before the preposition 'off'. Thus the sentence needs no improvement. Option 4 is the correct answer.

The idiom 'a red herring' means 'a distraction from the real issues.' Thus option 3 is the correct answer.

The idiom 'to go round the houses' means 'to do something in an inefficient way when there is a quicker, more convenient way.' Thus option 4 is the correct answer.

The word 'inquiry' means 'the asking of questions for informational purposes' and fits in the context. It is about seeing a couple is qualified for a loan or not. The word customary' means 'according to the customs or usual practices associated with a particular society, place, or set of circumstances' and does not fit here. The word 'initiative' means 'the ability to assess and initiate things independently' and is not correct here. The word 'aberration' means 'abnormal' and does not make any sense here. Thus option 1 is the correct answer.

The meanings of the words are:

Abstruse=> difficult to understand

Acclaim=> enthusiastic approval

Accede=> yield to another's wish or opinion

Accolade=> a tangible symbol signifying approval or distinction

Thus option 3 is the correct answer.

The meanings of the words are:

Accomplice=> a person who joins with another in carrying out some plan

Acquaint=> cause to come to know personally

Adduce=> advance evidence for

Ado=> a rapid active commotion

Thus option 1 is the correct answer.

The correct words are:

Assign=> allocate (a job or duty)

Dearth=> scarcity

Heresy=> belief or opinion contrary to orthodox religious (especially Christian) doctrine.

Longing=> wish

Thus option 3 is the correct answer.

The correct words are:

Excitation=> the action of exciting or the state of being excited; excitement.

Bolt=> a short, heavy arrow shot from a crossbow.

Gruesome=> horrifying

Forbid=> prohibit

Thus option 4 is the correct answer.

The meanings of the words are:

Exiguous=> small

Bombastic=> pompous

Petite=> small

Conventional=> old

Erroneous=> wrong

Thus option 2 is the correct answer.