Explanation:

The correct answer is option 'B', climber.

Definition:
A climber is a type of plant that has a weak stem and requires support from neighboring structures to grow vertically. Climbers have specialized structures such as tendrils, hooks, or twining stems that help them cling to surfaces and climb upwards.

Characteristics of climbers:
- Weak stem: Climbers have weak, flexible stems that cannot support their own weight. They rely on external support to grow vertically.
- Support from neighboring structures: Climbers use neighboring structures like trees, walls, fences, or trellises to climb and support their growth.
- Specialized structures: Climbers have adaptations like tendrils, hooks, or twining stems that enable them to attach themselves to surfaces and climb upwards.
- Examples: Some examples of climbers include money plant, ivy, morning glory, and passionflower.

Difference between creepers and climbers:
While both creepers and climbers require external support to grow vertically, there is a subtle difference between the two:
- Creepers: Creepers are plants with weak stems that grow horizontally along the ground or spread along the surface. They do not have the ability to climb vertically without the support of neighboring structures.
- Climbers: Climbers, on the other hand, have specialized structures that allow them to attach themselves to surfaces and climb upwards. They have the ability to grow vertically with the help of external support.

Conclusion:
In conclusion, the plants that have weak stems and require support from neighboring structures to grow vertically are called climbers. These plants have specialized structures that allow them to attach themselves to surfaces and climb upwards. Some examples of climbers include money plant, ivy, morning glory, and passionflower.