You are running a Hadoop cluster with MapReduce version 2 (MRv2) on YARN. You consistently
see that MapReduce map tasks on your cluster are running slowly because of excessive garbage
collection of JVM, how do you increase JVM heap property to 3GB to optimize performance?

A.
Yarn.application.child.java.opts-Xax3072m

B.
Yarn.application.child.java.opts=-3072m

C.
Mapreduce.map.java.opts=-Xmx3072m

D.
Mapreduce.map.java.opts=-Xms3072m

Explanation:
http://hortonworks.com/blog/how-to-plan-and-configure-yarn-in-hdp-2-0/