Vascular bundle with 2: 1 ratio of phloem and xylem is
Collateral
Amphivasal
Bicollateral
Amphicribral
A vascular bundle with a 2:1 ratio of phloem to xylem is referred to as an amphivasal vascular bundle. In an amphivasal bundle, the phloem surrounds the xylem, creating a ring-like structure. This arrangement allows for bidirectional movement of substances within the plant, with the xylem responsible for upward transport of water and minerals and the phloem for downward movement of sugars and other organic compounds. Hence, the correct answer is option 2.