Unlike Cycas and Pinus and most other gymnosperms Gnetum shows the presence of both tracheids and vessels in their xylem tissue and the absence of archegonia. Archegonia are altogether absent in the female gametophyte and vessels occur in the xylem along with the tracheids in the secondary wood. Thus, Gnetum shows affinities with angiosperms. Besides, it resembles angiosperms in several other aspects like free nuclear divisions in the embryo sac, two cotyledonous embryo, etc. Hence, the correct answer is option 'A'.

**Explanation:**

**Angiosperms** are flowering plants that produce seeds enclosed within a fruit. They are the most diverse group of land plants and include trees, shrubs, herbs, and grasses. Angiosperms are characterized by having flowers, double fertilization, and the production of fruits that contain seeds.

Among the given options, the plant nearest to angiosperms is **Gnetum**. Here is a detailed explanation:

**1. Gnetum:**
Gnetum is a genus of gymnosperms, which are seed-producing plants that do not produce flowers. Gymnosperms are a primitive group of plants that include conifers, cycads, and ginkgoes. Gnetum species are woody vines or shrubs found in tropical regions and are considered the closest relatives to angiosperms. While they do not produce flowers, they do have some angiosperm-like characteristics, such as vessels in their xylem and broad leaves.

**2. Taxus:**
Taxus is a genus of coniferous trees or shrubs commonly known as yews. They belong to the gymnosperm group and do not produce flowers. Yews have needle-like leaves and produce seeds in a fleshy structure called an aril. While they share some similarities with angiosperms, such as fruit-like structures, they are not true angiosperms.

**3. Cycas:**
Cycas is a genus of cycads, which are also gymnosperms. Cycads are palm-like plants with large compound leaves and produce cones for reproduction. They have separate male and female cones and do not produce flowers. Cycads are considered living fossils as they have remained relatively unchanged for millions of years.

**4. Pinus:**
Pinus is a genus of coniferous trees commonly known as pines. They are gymnosperms and do not produce flowers. Pines have needle-like leaves and produce cones for reproduction. They are major components of many forest ecosystems and have a long evolutionary history.

Based on the characteristics mentioned above, Gnetum is the closest plant to angiosperms among the given options. It shares some features with angiosperms, such as vessels in its xylem and broad leaves, making it a transitional plant between gymnosperms and angiosperms.