Assertion (A): Dictionaries in Python are mutable.

Reasoning (R): The data inside a dictionary is stored as the key:value pairs enclosed within the curly braces {}.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Both A and R are true but R is not the correct explanation of A.

Explanation
In Python, dictionaries are mutable, which means we can modify the key-value pairs, add new pairs, or remove existing pairs after the dictionary is created. Dictionaries are created using curly braces {}, and keys are separated from their corresponding values by a colon (:). Each key-value pair is separated by commas (,) within the dictionary.