What types of algorithms are difficult to express in MapReduce v1 (MRv1)?

What types of algorithms are difficult to express in MapReduce v1 (MRv1)?
A . Algorithms that require applying the same mathematical function to large numbers of individual binary records.
B . Relational operations on large amounts of structured and semi-structured data.
C . Algorithms that require global, sharing states.
D . Large-scale graph algorithms that require one-step link traversal.
E . Text analysis algorithms on large collections of unstructured text (e.g, Web crawls).

Answer: C

Explanation:

See 3) below.

Limitations of Mapreduce C where not to use Mapreduce

While very powerful and applicable to a wide variety of problems, MapReduce is not the answer to every problem. Here are some problems I found where MapReudce is not suited and some papers that address the limitations of MapReuce.