Need answer for only B and D

3. Type soundness for a simplfied programming language is typically described with "progress" and "preservation" theorems. Given an (unspecified) language with terms t, typeds T, contexts and an evaluation relation tt and a typing relation t:T, answer the following questions: (a) (2 points) State the "progress" theorem. (b) (2 points) Give a non-obvious problem in the language definition that would prevent "progress" from being true. (c) (2 points) State the "preservation" theorem. (d) (2 points) Give a non-obvious problem in the language definition that would prevent "preservation" from being true. (e) ( 2 points) How do progress and preservation work together to achieve that "well-typed programs don't go wrong