34. A Heap is based on a complete binary tree 35. All graphs are directed graphs Multiple Choice the question. Identify the choice that best completes the statement or answers 36. We deal with ADT's on three levels. On which level do we just need to know how to use the ADT? c. logical (or abstract) a. application (or user, client) d. implementation (or concrete) b. machine (or assembly) 37. we deal with ADTs on three levels. On which level do we deal with the "how" questions, as in how we represent the attributes and fulfill the responsibilities of the ADT? c. logical (or abstract) a. application (or user, client) d implementation (or concrete) b. machine (or assembly) 38. We deal with ADT's on three levels. On which level do we just deal with the "what" questions, as in what does the ADT model, what are its responsibilities, what is its interface? c, logical (or abstract) a. application (or user, client) d. implementation (or concrete) b. machine (or assembly) 39. The following sequence of operations essentially leaves a stack unchanged. c. push followed by top a. pop followed by push top followed by push b. pop followed by top objects can represent both information and behavior variables and constants d, methods and constructors b. classes and inheritance 41. Within an object, actions are modeled using a. classes c. methods b. variables The following is a "reference" type. a. int c. long. b, boolean d. String 43, A Stringlog is a. An array c. A container that holds strings