Double fertilization is

Options

A. Fusion of two male gametes with one egg
B. Fusion of one male gamete with two polar nuclei
C. Fusion of two male gametes of a pollen tube with two different eggs
D. Syngamy and triple fusion

Answer

### Step-by-Step Solution for the Question: "Double fertilization is"

1. **Definition of Double Fertilization**:
Double fertilization is a unique process in flowering plants where two fertilization events occur simultaneously. This involves the fusion of two male gametes with different female structures.

2. **Involvement of Male Gametes**:
In double fertilization, one male gamete (from the pollen grain) fuses with the egg cell (female gamete) to form a zygote. This process is known as **syngamy**.

3. **Involvement of Polar Nuclei**:
The second male gamete fuses with two polar nuclei present in the ovule. This fusion results in the formation of a triploid cell, which will develop into the endosperm, a tissue that nourishes the developing embryo. This process is referred to as **triple fusion**.

4. **Significance of Double Fertilization**:
The significance of double fertilization lies in the formation of both the zygote (which develops into the embryo) and the endosperm (which provides nutrition to the embryo). This dual fertilization ensures that the developing seed has the necessary resources for growth.

5. **Conclusion**:
Therefore, double fertilization in flowering plants consists of two processes: syngamy (fusion of one male gamete with the egg nucleus) and triple fusion (fusion of the second male gamete with two polar nuclei).

### Final Answer:
Double fertilization is the process in flowering plants where one male gamete fuses with the egg cell (syngamy) and the other male gamete fuses with two polar nuclei (triple fusion).

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