Step 1: Understand Plant Propagation Methods.
Plants can be propagated using various methods, including:
1. Regeneration: This refers to the natural process by which plants regrow damaged or lost parts, such as roots or shoots. It is not specific to growing new plants from tips.
2. Tissue Culture: This is a laboratory technique where plant tissues are grown in a nutrient medium to produce new plants. While effective, it does not involve using the tip of a plant.
3. Grafting: This involves joining parts of two different plants together to form a single plant. It is not specific to using the tip of a plant.
4. Layering: This is a method of propagation where a branch or stem is bent down and buried in soil while still attached to the parent plant. The tip of the branch is often used to initiate root growth, resulting in a new plant.
Step 2: Analyze Each Option.
Option (1): Regeneration — Incorrect, as regeneration is not specific to using the tip of a plant.
Option (2): Tissue culture — Incorrect, as tissue culture is a laboratory technique and does not involve using the tip of a plant.
Option (3): Grafting — Incorrect, as grafting involves joining two plants, not using the tip of a single plant.
Option (4): Layering — Correct, as layering specifically uses the tip of a plant to grow new roots and form a new plant.
Step 3: Final Answer.
$$
(4) \mathbf{\text{Layering}}
$$