Select one option which shows the data type of the variable mode in the algorithm shown in Figure 1.

Figure 1

1      mode ← USERINPUT
2      IF mode = 'focus' THEN
3          brightness ← 100
4      ELSE IF mode = 'relax' THEN
5          brightness ← 40
6      ELSE IF mode = 'night' THEN
7          brightness ← 10
8      ELSE
9          OUTPUT 'invalid mode'
10     ENDIF
11     FOR count ← 1 TO 3
12         IF brightness > 50 THEN
13             SET_LED('white')
14         ELSE
15             SET_LED('warm')
16         ENDIF
17     ENDFOR