4. Answer all of the following: (a) What information is stored in activation records? (b) Which of these information items are only in block-structured pro- gramming languages and why? (c) Name two programming languages where activation records are usu- ally stored on the stack and two where the activation records are usu ally on the heap. Page 2 of 7 Programming Languages Autumn 2012 (d) Describe why, in the latter two programming languages, it is necessary for the activation records to be stored on the heap