The tallest plant is
(a) Anthocephalus cadamba
(b) Acacia nilotica
(c) Eucalyptus regnans
(d) Rafflesia arnoldii

Options

A. Anthocephalus cadamba
B. Acacia nilotica
C. Eucalyptus regnans
D. Raffesia arnoldii

Answer

To determine which of the following plants is the tallest, we will analyze each option based on their height:

1. **Anthocephalus cadamba**:
- This tree can reach a height of about **45 meters**.
- It is commonly found in tropical forests, particularly in **Southern Asia**.

2. **Acacia nilotica**:
- The height of this tree ranges from **5 to 8 meters**, which is relatively small compared to the other options.
- It is primarily found in **West Asia**.

3. **Eucalyptus regnans**:
- This species is known as the **tallest angiosperm** and can grow up to **140 meters**.
- It is commonly found in the **Australia region** and is also referred to as **mountain ash**.

4. **Rafflesia arnoldii**:
- While this plant is known for producing the **largest flowers** among angiosperms, it is not the tallest plant.
- Its height is not significant compared to the others listed.

After evaluating the heights of all the options, it is clear that the tallest plant among the given choices is **Eucalyptus regnans**, which can reach heights of up to **140 meters**.

**Final Answer**: (c) Eucalyptus regnans

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