In Drosera, movement of tentacles are

The correct option is Thigmonastic.

Step-by-step Explanation:

1. Understanding the Stimulus:
Drosera, commonly known as sundew, is a genus of carnivorous plants. The leaves of these plants are covered with glandular tentacles that secrete a sticky mucilage to trap insects. When an insect lands on these tentacles, the physical touch or mechanical contact acts as a stimulus.

2. Mechanism of Movement:
In response to the mechanical stimulus of touch, the tentacles bend or curve inward toward the center of the leaf to secure the prey and maximize contact with digestive enzymes. A movement that occurs in response to touch or contact is referred to as a thigmonastic (or haptonastic) movement. Because the direction of the movement is determined by the anatomy of the plant organ rather than the direction of the stimulus, it is a nastic movement, specifically thigmonastic.

3. Analyzing the other options:
• Thermonastic: Response of plant parts to changes in temperature (e.g., the opening and closing of tulip flowers).
• Seismonastic: Response to shock, wind, or rapid vibration (e.g., the folding of leaves in Mimosa pudica).
• Photomastic (Photonastic): Response to light intensity variations (e.g., the opening of flowers in daylight and closing at night).

Therefore, the movement of tentacles in Drosera in response to contact with prey is classified as thigmonastic.