Options A and B are both correct, with slightly different meanings depending on the context of the sentence, because suffixes -ful and -less both form adjectives. In 'shameful behaviour', the adjective modifies the noun 'behaviour' meaning 'the behaviour causing shame'. In 'shameless attempt', the adjective attributes the meaning 'lack of shame' to the noun 'attempt'. Options C and D are incorrect because the words 'shamiable' and 'shamely' do not exist in the English language.