Posting the collection and supplier payment into their existing accounts produces $16,000 on each side of the ending trial balance.
This adds receipt and payment activity without reducing the receivable and payable accounts to their ending balances.
The $1,000 payment reduces but does not eliminate the $3,000 payable; forcing the other credit balances to absorb the difference is unsupported.
Posting reorganizes 4 balanced entries into 8 account lines; it does not create additional transactions or turn total activity into ending balances.
Answer: A
Cash is $9,000 opening plus $2,000 collection minus $1,000 supplier payment, or $10,000. Supplies are $3,000. Accounts Receivable are $5,000 minus the $2,000 collection, or $3,000. Accounts Payable are $3,000 minus the $1,000 payment, or $2,000 credit. Owner, Capital is $9,000 and Service Revenue is $5,000, producing $16,000 on each trial-balance side.