B. vertebrates and invertebrates.
Saliva,unprotected intercourse,contact with infected blood (blood transfusion)
and women with an unborn child.
The answer is <span>D- thigmotropism
</span>
Tropism is plant growth in a response to a stimulus.
Through the process of elimination:
A - phototropism is plant growth in a response to light.
B - Photoperiodism is an organism reaction to the lengths of days and nights.
C - Gravitropism is plant growth in a response to gravity.
D - Thigmotropism is plant growth in a response to contact
Since <span>a grapevine makes a contact with a fence, this is an example of thigmotropism.</span>
Vessel walls are very thin because they let ease of transfer of molecules to these tissues. This is why <span>capillaries and not arteries or veins are found in alveolar, nephrons, and villi.</span>
