First UNAL exercise...

main.java

package com.first;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

public class Main {

    private static final String FILENAME = "c::\\path-to\\text.txt";
    private static Map<String, Integer> counter = new HashMap<String, Integer>();

    public static void main(String[] args) {
        try (BufferedReader br = new BufferedReader(new FileReader(FILENAME))) {

            String sCurrentLine;

            int i = 0;
            int maxLines = -1;
            while ((sCurrentLine = br.readLine()) != null) {
                if (maxLines == -1) {
                    maxLines = Integer.parseInt(sCurrentLine);
                    continue;
                }
                if (i < maxLines) {
                    String maxLetter = readLine(sCurrentLine);
                    System.out.println("The most selected option in the question # " + Integer.toString(i) + " is "
                            + maxLetter + " with " + Integer.toString(counter.get(maxLetter)) + " selections");
                    counter.clear();
                }
                i++;
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static String readLine(String line) {
        String[] letters = line.split("");
        for (String letter : letters) {
            counter.put(letter, counter.getOrDefault(letter, 0) + 1);
        }
        return Collections.max(counter.entrySet(), Comparator.comparingInt(Map.Entry::getValue)).getKey();
    }
}