Which of the following is a valid identifier:i. 9type ii. _type iii. Same-type iv. True

In Python, a valid identifier must follow these rules:

1. It can only contain alphanumeric characters (a-z, A-Z, 0-9) and underscores (_).
2. It cannot start with a number.
3. It cannot be a reserved word.

Let's check each option:

i. 9type: This is not a valid identifier because it starts with a number.

ii. _type: This is a valid identifier. It starts with an underscore and contains only alphanumeric characters.

iii. Same-type: This is not a valid identifier because it contains a hyphen (-), which is not an alphanumeric character or an underscore.

iv. True: This is not a valid identifier because it is a reserved word in Python.

So, the only valid identifier among the options is _type.