The correct answer is: A. map
The map method is the main method of the Mapper class. It is responsible for processing the input data and generating the intermediate key-value pairs. The map method is called once for each line of input data.
The reduce method is called once for each intermediate key. It is responsible for merging the intermediate key-value pairs and generating the final output.
The mapper and reducer are two of the main components of the MapReduce programming model. The mapper is responsible for processing the input data and generating the intermediate key-value pairs. The reducer is responsible for merging the intermediate key-value pairs and generating the final output.
The MapReduce programming model is a programming model and an associated implementation for processing and generating large data sets. Users specify a map function that processes a key/value pair to generate a set of intermediate key/value pairs, and a reduce function that merges all intermediate values associated with the same intermediate key.