English

The correct pronoun to use after 'possibility of' is the object pronoun 'them' because it follows a preposition ('of'). 'They' is a subject pronoun and incorrect here, while 'theirs' and 'their' are possessive forms and do not fit grammatically.

The term 'Obsolete' means something that is no longer in use or out of date, which directly answers the question. The other options do not match this meaning.

The phrase "At the drop of a hat" means to do something immediately or without any delay, which corresponds to option C: "Done in an instant." Option B is incorrect because it implies ease or lack of preparation, which is not the meaning of the phrase.

The phrase "far cry from" means something is very different from or distant from something else, making option D the correct choice.

The correct preposition to use with 'feel sorry' when expressing sympathy is 'for'. Therefore, 'I feel sorry for his kids' is correct.

The correct preposition to use with 'surprised' in this context is 'at'. We say 'surprised at his result' to indicate the cause of the surprise.

The correct preposition to express annoyance or frustration with something is 'of'. The phrase 'I am sick of job' means being tired or fed up with the job. Although the sentence is missing an article before 'job', the focus is on the preposition, and 'of' is the correct choice among the options.

"Ace in the hole" is an idiom meaning a hidden advantage or a secret strength that can be used when needed. This matches option A exactly.

The correct modal verb to express a past prediction or expectation is 'would'. 'Shall' and 'will' are used for future tense, but 'would' is the past form of 'will' and fits the past context indicated by 'knew'.

"Go Dutch" is an idiomatic expression meaning that each person pays for their own share, especially when sharing the cost of a meal or outing equally.