Complete the sentence: He could hardly believe his luck when he found the wallet ______.

• A. there
• B. therefore
• C. therein
• D. thereafter

Answer: (A)

The key idea is choosing a word that shows location. After “found the wallet,” you need an adverb that tells us where—“there” does exactly that. It refers to the place already implied or mentioned and sounds natural in everyday English: He could hardly believe his luck when he found the wallet there.

The other options don’t fit the meaning or the flow. “Therefore” signals a consequence, not location. “Therein” means in that place and is quite formal, making the sentence feel odd in this everyday context. “Thereafter” means after that time, which shifts the sense to time rather than place and doesn’t work with the verb phrase here.