Final answer:
Size(b) is not a main difference between Monocots and Eudicots; distinguishing factors include the number of cotyledons, venation patterns, and vascular arrangement.
Step-by-step explanation:
Size(b) is NOT a main difference between Monocots and Eudicots. The main differences between these two groups of flowering plants include the amount of cotyledons, venation patterns in leaves, and their vascular arrangement. Monocots are characterized by having a single cotyledon, leaves with parallel venation, and vascular tissue that is scattered in the stem. In contrast, Eudicots, or true dicots, have two cotyledons, leaves with a network of veins (reticulate venation), and vascular tissue that typically forms a distinct ring within the stem.