Cirral activity of two barnacles in relation to temperature are given above, which one of the following is the most appropriate explanation of the figure ?

Options

A. Both the barnacles maintain their activity under narrow range of temperatures.
B. Both the species are more active above `20^@C`.
C. There is a rapid depression of activity when temperature increases above `6^@C`.
D. Upper intertidal species show greater thermal tolerance than lower intertidal species.

Answer

D