If 'dog' is called 'lion', 'lion' is called 'bison', 'bison' is called 'snake', 'snake' is called 'mongoose', 'mongoose' is called 'crocodile', then which of the following may be domesticated as a pet ?

In option A, the name of the animal is Lion and we know that Dog is called Lion. Hence, the actual animal in the option A is a dog. 

In option B, the name of the animal is Bison and we know that Lion is called Bison. Hence, the actual animal in the option B is a Lion.

In option C, the name of the animal is Snake and we know that Bison is called Snake. Hence, the actual animal in the option C is a Bison.

In option D, we don't know the actual animal as the name Dog is not assigned to any of the animals in the question. 

In option E, the name of the animal is Mongoose and we know that Snake is called Mongoose. Hence, the actual animal in the option D is a Snake.

Hence, we can only pet a dog which is called Lion (given). 

Option A.