Step 1: Understanding the Concept:
Food adulteration is the practice of adding a substance to a food item to increase its quantity, lower its quality, or make it appear better than it is, often for economic gain. The term can also be used more broadly to include any fraudulent or deceptive practice in selling food.
Step 2: Detailed Explanation:
- Selling fake as real: This involves substituting a genuine product with a counterfeit or entirely different, cheaper substance (e.g., selling papaya seeds as black pepper). This is a form of adulteration.
- Selling by wrong labelling: Misbranding or providing false information on a label about ingredients, nutritional value, or expiry date is a deceptive practice considered under adulteration laws.
- Selling by mixing prohibited colours: Adding non-permitted or harmful dyes to food (e.g., Metanil yellow in turmeric powder) to enhance its appearance is a dangerous form of adulteration.
All the given options are examples of adulteration or fraudulent practices in the food trade.
Step 3: Final Answer:
All the listed activities are examples of adulteration. Therefore, the correct option is 'All of these'.