The question asks us to identify a set of organs that do not contribute to the digestive process. To answer this, let's review the role of each organ in the provided options.

Explanation of Each Organ:

1. Small Intestine: The small intestine plays a crucial role in digestion. It is where most of the digestion and absorption of nutrients occur.
2. Large Intestine: While the large intestine primarily absorbs water and electrolytes, it also processes waste. However, it does not play a direct role in the digestion of food.
3. Rectum: The rectum stores feces before they are excreted. It does not participate in digestion or nutrient absorption.
4. Oesophagus: The oesophagus is a muscular tube that transports food from the throat to the stomach. It does not digest food but is part of the digestive system. Its primary function is to act as a conduit.
5. Buccal Cavity: The buccal cavity (mouth) initiates digestion by mechanically breaking down food and mixing it with saliva. It is the starting point of digestion.

Analysis of Options:

1. Small intestine, large intestine, rectum: The small intestine is involved in digestion, so this option can't be correct.
2. Oesophagus, large intestine, rectum: The oesophagus and rectum do not contribute directly to digestion. The large intestine only absorbs remaining nutrients and water.
3. Large intestine, small intestine, oesophagus: The small intestine digests food, thus this option isn't correct.
4. Buccal cavity, oesophagus, rectum: The buccal cavity initiates digestion, so this choice can't be correct.

Conclusion: Based on the above analysis, the correct answer is Oesophagus, large intestine, rectum as these organs do not directly contribute to the digestive process.