Step 1: Understanding Fertilization Terminology:
Oogamy: Fusion of a large non-motile female gamete (egg) with a small male gamete. This is characteristic of Angiosperms.
Siphonogamy: The transport of male gametes to the female gamete through a **pollen tube**. This occurs in Gymnosperms and Angiosperms.
Zooidogamy: Fertilization involving motile male gametes (swimming sperm), found in Algae, Bryophytes, Pteridophytes, and some Gymnosperms (e.g., \textit{Cycas}), but **not** in Angiosperms.
Step 2: Conclusion:
Angiosperms exhibit **Siphonogamy** (pollen tube carries sperm) and **Oogamy** (egg is fertilized). Thus, it is Siphonogamous oogamy.