a) If you need to query the database for exact, mathematically valid matches, use Exact Precision
b) If you regularly need to perform server-side arithmetic on monetary data, the exact precision model may be appropriate
c) If you need to query the database for exact, mathematically valid matches, use Ambiguity Precision
d) None of the mentioned

Answer: c
Explanation: If you need to be able to do server-side arithmetic, e.g., $inc, $mul, and aggregation framework arithmetic, use Exact Precision.