If A is the set of whole numbers and B is the set of natural numbers, then `(A-B)` is __________ set.
(singleton/null)

Answer

To solve the question, we need to determine what the set \( A - B \) represents, where \( A \) is the set of whole numbers and \( B \) is the set of natural numbers.

### Step-by-step Solution:

1. **Define the Sets**:
- The set of whole numbers \( A \) is defined as:
\[ A = \{0, 1, 2, 3, 4, \ldots\} \]
- The set of natural numbers \( B \) is defined as:
\[ B = \{1, 2, 3, 4, \ldots\} \]

2. **Understand the Operation \( A - B \)**:
- The operation \( A - B \) means we take all the elements in set \( A \) and remove all the elements that are also in set \( B \).

3. **Perform the Set Difference**:
- Start with set \( A \):
\[ A = \{0, 1, 2, 3, 4, \ldots\} \]
- Remove elements of set \( B \) from set \( A \):
- Remove \( 1 \): \( A \) becomes \( \{0, 2, 3, 4, \ldots\} \)
- Remove \( 2 \): \( A \) becomes \( \{0, 3, 4, \ldots\} \)
- Remove \( 3 \): \( A \) becomes \( \{0, 4, \ldots\} \)
- Continue this process for all natural numbers.
- The only element that remains in \( A \) after removing all elements of \( B \) is \( 0 \).

4. **Identify the Resulting Set**:
- After performing the set difference, we have:
\[ A - B = \{0\} \]

5. **Classify the Resulting Set**:
- The set \( \{0\} \) contains exactly one element. Therefore, it is classified as a **singleton set**.

### Final Answer:
Thus, \( (A - B) \) is a **singleton set**.

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