Thigmotropism is the oriented growth of an organism in response to _________.

Thigmotropism is the oriented growth of an organism in response to physical contact.
Thigmotropism is a type of tropism, which is a growth or movement response of an organism in response to a particular stimulus. In the case of thigmotropism, the stimulus is physical contact with an object or surface. The organism responds by growing or orienting itself in a particular direction in relation to the contact stimulus. Therefore, physical contact is the factor that triggers thigmotropism.