The correct option is A White Siberian tigers are rare to find; they usually attract visitors to a zoo.
When there are more than two adjectives in a sentence, and when those adjectives modify the same noun, the order of adjectives is according to the case it's in: adjectives of quantity, quality, size, age, shape, colour, proper adjective (nationality, place of origin, etc.), qualifier.
In the given sentence, the adjective of colour 'white' is placed after the proper adjective 'Siberian' which is wrong. It must be placed before the proper adjective, according to the explanation given above. Hence option A is incorrect and B is correct.
Option C is incorrect because it is placed after the verb 'find', thereby functioning as the object, but an adjective cannot function as an object.
Option D is incorrect because the adjective is modifying the noun 'visitors' instead of the noun 'tiger'. The sentence is illogical, as it points out people of a particular race for a general statement (white tourists).