I believe Nixon
I suppose that you think to oxygen.
Cell membrane
A rattlesnake is most active once the Sun has risen and warmed the environment. In cold conditions, snakes are rather torpid and are unlikely to be very active.
A user account. Without a user account object defined in the active directory a user cannot log on and gain access to network resources.
Regulating the workplace( gradpoint
The comparative adjective form is more active. The superlative adjective form is most active.
nervous
hypothalamus
Most scientists were not
regulating Industry
No. Be is active, but is nowhere near the most active element.
nervous tissue