Hadoop MapReduce - Sample Interview Question (Junior Level)

Is it possible to write 'map only' hadoop jobs?  (without the reduce phase) 
  1. No
  2. Yes, just turn off the reducer by
    job.setNumReduceTasks(0)
  3. Yes, the only solution for that is
    to use IdentityReducer.
Tests in Hadoop MapReduce for Juniors

Test Name Difficulty Time (minutes) No. of Questions
Hadoop MapReduce Online Test for Juniors Hadoop MapReduce Junior 20 10