Step 1: Understanding the Question:
The question asks for a key indicator or "maturity index" that growers use to decide the right time to harvest bananas.
Step 2: Key Formula or Approach:
Bananas are harvested when they are mature but still green (climacteric fruit). The maturity index must be a reliable physical sign that indicates the fruit has reached this stage. The approach is to evaluate which option represents this sign.
Step 3: Detailed Explanation:
(C) Angularity of fingers: This is the most widely used visual indicator. When bananas (the "fingers") are immature, they have sharp, distinct angles or ridges. As they mature and the pulp fills out, these angles become less prominent, and the fruit appears more rounded and plump. The disappearance of this angularity indicates the banana is ready for harvest.
Let's analyze other options:
(A) Flowering stage: This marks the beginning of fruit development, not maturity.
(B) Fruit color change: The change from green to yellow happens during ripening, which occurs after the banana has been harvested.
(D) Leaf fall: This is generally a sign of plant health or age, not fruit maturity.
Step 4: Final Answer:
The change in the angularity of the banana fingers is the primary maturity index for harvesting. Therefore, option (C) is correct.