Meaning: 'Became' means to have come to be or to have undergone a change in state, indicating that dog shows transitioned into a more popular and lucrative activity in the past.

Wrong options:

• become: 'Become' is the base form of the verb and does not fit the past tense context required here.
• becoming: 'Becoming' is a gerund or present participle, which does not convey the completed action needed in this sentence.
• have become: 'Have become' is present perfect tense, which implies an ongoing relevance to the present, not suitable for the historical context of the sentence.

Correct answer: for

Explanation: The preposition 'for' indicates the purpose of the selective inbreeding, which is to achieve specific traits. This fits grammatically and contextually, as it shows the intention behind the breeders' actions.

Meaning: 'For' is used to indicate the purpose or reason for something, in this case, the traits that breeders are aiming to achieve through selective inbreeding.

Wrong options:

• with: 'With' suggests accompaniment or association, which does not convey the purpose of inbreeding as effectively as 'for.'
• by: 'By' indicates the means or method, which does not fit the context of aiming for specific traits.
• of: 'Of' indicates belonging or association, which does not express the purpose of selective breeding.

Correct answer: that

Explanation: The word 'that' is a relative pronoun used to introduce a defining clause, providing essential information about the genetic abnormalities. It fits grammatically and contextually as it connects the abnormalities to the potential consequences mentioned in the sentence.

Meaning: 'That' is used to introduce a clause that specifies or identifies something, in this case, the genetic abnormalities that can lead to health issues.

Wrong options:

• then: 'Then' indicates a time sequence and does not fit the grammatical structure needed to introduce a clause about genetic abnormalities.
• there: 'There' is an adverb indicating place or existence, which does not serve the purpose of connecting the clause to the subject.
• than: 'Than' is a conjunction used for comparisons, which does not fit the context of defining the abnormalities.

Correct answer: too

Explanation: The word 'too' is an adverb that indicates an excessive degree, fitting the context of breeders being overly willing to overlook health problems. It aligns grammatically and contextually with the sentence's tone and meaning.

Meaning: 'Too' means excessively or more than is necessary, indicating that breeders are willing to overlook health issues to an undesirable extent.

Wrong options:

• ever: 'Ever' implies at any time, which does not convey the excessive willingness indicated in this context.
• more: 'More' suggests an increase but does not capture the excessive nature of the willingness described.
• over: 'Over' is a preposition that does not fit grammatically as an adverb in this context.

Correct answer: no

Explanation: The word 'no' is used to indicate the absence of something, fitting the context of the sentence which discusses the lack of incentive for breeders to change their practices. It aligns grammatically and contextually with the overall message.

Meaning: 'No' means not any or not one, indicating that there is a complete lack of incentive for breeders to alter their practices.

Wrong options:

• some: 'Some' implies a certain amount or degree, which contradicts the intended meaning of absence of incentive.
• any: 'Any' suggests the possibility of at least one, which does not fit the context of a complete lack of incentive.
• none: 'None' indicates zero quantity but is less commonly used in this context compared to 'no'.