The correct option is B since yesterday morning
Let’s examine the sentence: “I haven't eaten anything ____ .” The sentence needs a time to complete its sense. We see the options, ‘for yesterday morning’ in Option C and ‘for five o’clock’ in Option D are incorrect for is used with specific time. We use ‘for’ when we measure the duration – when we say how long something lasts. Options C and D are giving specific time and not duration with ‘for’ and hence, they are incorrect. ‘Since’ gives the starting point of actions, events or states. In Option A, ‘since’ is not giving the starting point of the action and hence, is incorrect. Option B correctly gives the starting point of action with ‘since’ and hence, is the right answer.