Step 1: Formula.
\[
\text{Creditors Turnover Ratio} = \frac{\text{Net Credit Purchases}}{\text{Average Trade Creditors}}
\]
Step 2: Explanation.
The ratio measures how quickly a firm pays its creditors. Therefore, only credit purchases are considered, not cash purchases.
Step 3: Eliminate wrong options.
- Credit sales or cash sales: Related to debtors, not creditors.
- Cash purchase: Not relevant, as no credit is involved.
Step 4: Conclude.
Hence, creditors turnover ratio includes total credit purchases.
Final Answer:
\[
\boxed{\text{Total credit purchase}}
\]