The correct answer is feeble.
- Sturdy means "strong and well-built; able to withstand strain or stress."
- Feeble means "weak and delicate; easily broken or damaged."
In the sentence, the word "sturdy" is being used to describe the old house. However, the sentence tells us that the house was so weak that it could be shattered into pieces with a single blow. This means that the house was not sturdy, but rather feeble.
The other words do not have the same meaning as sturdy, so they are not its antonyms.
- Wry means "having a twisted or ironic meaning."
- Competent means "having the necessary skills or knowledge to do something successfully."
- Subdued means "not loud or showy; restrained."
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