Question: Mark four points at equal distances along the bottom edge of the paper in the horizontal direction: A (leftmost), B, C, and D (rightmost). Maintain the same procedure and rhythm as shown in the diagram, and continue applying the heat source until the entire paper undergoes the same process. If a heat-sensitive sealing wax with the same melting point is placed at these four points, which one will melt last?
A. Point A (leftmost)
B. Point B (slightly left)
C. Point C (near the center)
D. Point D (rightmost)
Clues:
1. The image shows a white piece of paper with four golden-brown Chinese characters ("新年快乐") on it.
2. The characters have a different color and texture from the rest of the white paper.
3. A comparison between the left and right panels shows that the characters were initially faint or invisible and then became visible, suggesting they were revealed by a process like heating.
4. The substance forming the characters is likely an organic compound (like sugar or lemon juice) used as invisible ink, which serves as a rich food source.
Answer: D
Category: Chemistry