The phrase 'used to' is often followed by an infinitive or gerund, to indicate that you're accustomed to something. In the given sentence, the person is not used to a certain habit. From the options, 'getting up' states a habit. 'Get up' and 'got up' state the actions, as 'get' and 'got' are verbs. 'Getting', on the other hand', is a gerund. 'Getting up' is the object of the verb phrase 'used to'.

Hence, option B is correct and A and C are incorrect.

'Be getting up' also states an action, as the verb 'be' is present. Since the verb phrase 'used to' should be followed by an object, rather than another verb phrase 'be getting up', option D is incorrect.