Final answer:
The correct answer is option A. A twig's age can be determined by the number of apical bud scar rings, which are left when the apical bud falls off at the end of a growing season. Each ring represents a year of growth, making it the most accurate option for age determination among those provided.
Step-by-step explanation:
To determine a twig's age, one can look at certain characteristics that are indicative of the passage of time. The most accurate among the options provided is the number of apical bud scar rings. Each year a tree produces a new layer of growth, marked by the formation of these rings. As a twig grows, the apical bud develops, and when it falls off at the end of the growing season, it leaves behind a scar. Counting these scar rings on a twig allows you to determine how many growing seasons or years the twig has seen.
Length of internodes can vary with environmental conditions and is not a reliable indicator of age. The number of leaf scars can tell you how many leaves were there but does not directly relate to the age. The number and arrangement of axillary buds do not necessarily change with age and are also not reliable for age determination. Hence, the correct option for determining a twig's age is the number of apical bud scar rings.