Which of the following is/are wrong?

a) In maize root xylme is tetrarch; in bean root it is polyarch b) Xylem and phloem are arranged radially alternating with each other c) Xylem is usually tetrarch in dicot root, and polyarch in monocot root

Statement (a) is wrong because it reverses the facts - maize is a monocot with polyarch xylem, while bean is a dicot with tetrarch xylem. Statement (b) is correct because xylem and phloem are radially arranged in roots. Statement (c) is correct because dicot roots typically have tetrarch xylem while monocot roots are polyarch.