Answer :
Answer:
A). Hypoxia.
Explanation:
Hypoxia is characterized as the condition in which tissues are deprived of an adequate supply of oxygen. As per this definition, hypoxia would be the process that is most likely to occur in the plant's leaves when it is revealed to a minimum level of 1 or 2% of oxygen. The lack of oxygen in such states reaches the tissues. One of the advanced stages of this process is 'anoxia; where there is a complete absence of 'oxygen' that enhances the ecological stress. Thus, option A is the correct answer.