The woman refused to testify … her husband.

Analyze the question: We need the preposition that correctly completes "refused to testify __ her husband." This tests prepositions that collocate with the verb testify.

Explain the concept: The verb testify takes different prepositions depending on meaning:

• testify against someone means to give evidence that harms them or supports a case against them.
• testify for someone means to give evidence in their favour.
• testify to something means to confirm or bear witness to a fact.

Solution:

• A. testify from is not a standard collocation.
• B. testify in is used with a place or case, as in "testify in court", but it doesn't fit before "her husband".
• C. testify at is used with an event or place, as in "testify at the trial", not before a person.
• D. testify against her husband is correct, because it is the natural phrase for giving evidence to the disadvantage of a person in court.

The sentence reads: "The woman refused to testify against her husband." This makes sense because many people are reluctant to give evidence that could harm a spouse.

Answer: D. Against

Tip: For prepositions after verbs, memorise common pairs. For courtroom language, remember testify against (to harm), testify for (to help) and testify in court (location). If the object is a person, think against or for.