The correct answer is D. Tactile.

Vibrissae, also known as whiskers, are specialized hairs found on the faces of many mammals, including rats. They are highly sensitive to touch and play a crucial role in:

- Spatial awareness and navigation

- Detecting objects and obstacles

- Measuring distances and textures

Rats use their vibrissae to gather information about their environment and make precise movements.

The other options are not accurate:

A. Photosensitive refers to sensitivity to light, which is not a characteristic of vibrissae.

B. Radiosensitive refers to sensitivity to radiation, which is also not relevant to vibrissae.

C. Chemoreceptive refers to sensitivity to chemical stimuli, such as smells or tastes. While rats have a keen sense of smell, their vibrissae are not chemoreceptive.