Introduction:
In Python, a set is an unordered collection of unique elements. Sets are implemented using a hash table, which allows for efficient membership testing, insertion, and deletion. This response will explain why option A is the correct answer.

Explanation:
The correct statement about sets in Python is that sets can contain duplicate elements. Let's consider the other options and evaluate why they are incorrect:

a) Sets can contain duplicate elements:
- Sets in Python are unordered collections of elements, meaning that the elements do not have a specific order or sequence.
- However, the most important property of sets is that they only contain unique elements. This means that if you try to add a duplicate element to a set, it will be ignored and not added to the set.
- For example, if we create a set with duplicate elements, Python will automatically remove the duplicates:
```
my_set = {1, 2, 2, 3, 4, 4, 5}
print(my_set) # Output: {1, 2, 3, 4, 5}
```
- This property of sets makes them useful in scenarios where we need to eliminate duplicates from a collection of elements.

b) Sets are ordered collections:
- This statement is incorrect. Sets in Python are unordered collections, which means that the elements in a set do not have a specific order or sequence.
- If you need to maintain the order of elements, you can use a different data structure like a list.

c) Sets can only contain numeric values:
- This statement is incorrect. Sets in Python can contain elements of any data type, including numeric values, strings, tuples, etc.
- For example, we can create a set with a mix of different data types:
```
my_set = {1, 'apple', (1, 2)}
```

d) Sets can be accessed using index values:
- This statement is incorrect. Sets in Python do not support indexing because they are unordered collections.
- If you need to access elements by index, you should use a different data structure like a list or tuple.

Conclusion:
The correct statement about sets in Python is that sets can contain duplicate elements. Sets are unordered collections that only contain unique elements. They can include elements of any data type and do not support indexing.