On hot, dry days, guard cells often close microscope openings in plant leaves, conserving water This is an example - Science - Responses Like This Too!

Question

On hot, dry days, guard cells often close microscope openings in
plant leaves, conserving water This is an example of

1: Environment factors causing gene mutation in plants

2: Finite resources acting as selecting agents for evolution

3: A feedback mechanism for maintaing homeostasis

4: Differentiation in plants as a result of stimuli

Aditya Sharma · Answer

1 It is basically an adaptation but this has changed the gene pool
of desert plants or xerophytes