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

Wrong options:

• become: The word 'become' is the base form of the verb and does not fit the past tense context required here.
• becoming: 'Becoming' is the present participle form and suggests an ongoing action, which does not match the completed action described in the sentence.
• have become: 'Have become' is the present perfect tense, which implies a connection to the present, but the sentence specifically refers to a past event.

Correct answer: for

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

Meaning: 'For' is used to indicate the purpose of an action, 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 breeding for specific traits.
• by: 'By' indicates the means or method of doing something, but does not express the goal of achieving certain traits.
• of: 'Of' indicates belonging or association, which does not fit the context of aiming for specific traits.

Correct answer: that

Explanation: The word 'that' is a relative pronoun used to introduce a defining clause, linking the genetic abnormalities to the consequences they can cause. This fits grammatically and contextually, as it specifies which abnormalities are being discussed.

Meaning: 'That' is used to introduce a clause that provides essential information about the noun it follows, in this case, genetic abnormalities that lead to serious health issues.

Wrong options:

• then: 'Then' indicates a sequence in time and does not fit the grammatical structure needed to introduce a clause about genetic abnormalities.
• there: 'There' is used to indicate a place or existence, which does not relate to the context of describing genetic abnormalities.
• this: 'This' refers to something specific and does not appropriately introduce the clause about the consequences of genetic abnormalities.

Correct answer: too

Explanation: The word 'too' is an adverb that indicates an excessive degree, fitting well in the context of breeders being overly willing to overlook health problems. This aligns with the tone of the sentence, which critiques their actions.

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

Wrong options:

• ever: 'Ever' implies at any time and does not convey the degree of willingness required in this context.
• more: 'More' suggests a comparative degree but does not fit the context of willingness to overlook health problems.
• over: 'Over' does not function as an adverb in this context and does not convey the intended meaning of excessive willingness.

Correct answer: no

Explanation: The word 'no' indicates the absence of incentive, which fits the context of the sentence discussing the lack of motivation for breeders to change their practices. This aligns with the overall negative sentiment regarding the situation.

Meaning: 'No' means not any or none, indicating that there is a complete lack of incentive for breeders to alter their cruel practices.

Wrong options:

• some: 'Some' implies a certain amount or degree, which contradicts the intended meaning of a complete lack of incentive.
• any: 'Any' suggests at least one, which does not fit the context of indicating a total absence of incentive.
• none: 'None' is similar to 'no' but is less commonly used in this context and does not fit as smoothly into the sentence structure.