To solve this problem, we need to analyze each statement about vascular bundles and determine which ones are correct. Let's examine each statement:$\newline \bullet$(a) In roots, xylem and phloem in a vascular bundle are arranged in an alternate manner along different radii.$\newline$ - This is true for roots, where the arrangement is radial. Xylem and phloem are arranged alternately along different radii.$\newline \bullet$(b) Conjoint closed vascular bundles do not possess cambium.$\newline$ - This is true. In closed vascular bundles, there is no cambium present, which means they do not have the ability to undergo secondary growth.$\newline \bullet$