a) An environment is a collection of (symbol, value) pairs, i.e. x is a symbol and 3.14 might be its value
b) If the value of a symbol is not found in the environment in which a function was defined, then the search is continued in the child environment
c) After the top-level environment, the search continues down the search list until we hit the parent environment
d) Dynamic scoping turns out to be particularly useful for simplifying statistical computations
Answer: a