A 1-to-1 join between two equally sized datasets with perfect key matches yields an output that has what relationship to the inputs?

• A. The output will have the same number of features as each input dataset.
• B. The output will be the product of the input sizes.
• C. The output will be the sum of the input sizes.
• D. The output will be double the input size.

Answer: (A)

In a 1-to-1 join, each input feature pairs with exactly one feature from the other input based on a common key. When the two inputs are the same size and every key matches perfectly, every feature has a single partner, so you produce one output feature for every input feature. The result contains all fields from both inputs (often with suffixes to handle overlapping names), but the number of rows (features) remains equal to the size of the inputs. If there were missing matches or duplicates, the row count could differ, but with perfect one-to-one matching and equal sizes, the output row count stays the same as each input.