The correct option is
B Shy
The given word 'timid' means 'easily alarmed, shy'.From the options, Option D: 'shy' best expresses the meaning of the given word. Hence option D is correct.
Option A: 'Fast' means 'to move or function rapidly'.
Option B: 'Slow' means 'moving in a less than usual speed', 'lack of speed'.
Option C: 'Bold' means 'courageous and daring'.
These words do not mean the same as the given word, hence options A, B and C are incorrect.