After a Biology Field Trip,you Make a Thin Section of a Flowering

Multiple Choice

After a biology field trip,you make a thin section of a flowering plant stem.You observe these two main sets of cells: the lower set of cells are large,have thick walls,and test positive for the lignin molecule,while the smaller,but uniform red cells do not have lignin.From this evidence,you conclude that the larger cells with lignin are

A) cuticle.
B) stomata.
C) rhizoids.
D) xylem.
E) phloem.