Answer:
Is released into the air through stomata
Explanation:
Oxygen and hydrogen both exists as gaseous molecules in the atmosphere. However, one of them (oxygen) is a product of photosynthesis while the other (hydrogen) is one of the constituents of the molecule that starts the process of photosynthesis. 
According to this question, the X used in the attached diagram is the role of oxygen in photosynthesis. Oxygen is released as a product of photosynthesis and goes out of the plant into the air via the STOMATA. Hence, the gas released into the air via stomata is OXYGEN.
 
        
             
        
        
        
Answer:
Water vapor is a greenhouse gas, which absorbs the heat radiated from the earth's surface. It allows less heat to escape back to space by trapping the heat energy in the lower atmosphere and keeps the atmosphere warm.
Explanation:
Water vapor is formed through a process called evaporation. In this process, water from the ocean, rivers, and lakes evaporates to become water vapor using the energy from the sun. Water vapor also moves into the atmosphere by transpiration (plants) and sublimation (snow and ice).
The water vapor cools down and transforms into water droplets by a process called condensation, as it rises high in the atmosphere where the air is cooler. This water droplets that formed by condensation make up clouds.
When the earth’s surface get heated by the sunlight, some of the heat radiates back into the atmosphere and most of this heat is absorbed by gases in the atmosphere called green house gases. This process is called greenhouse effect, which keeps the earth warm. The green house gases mainly consists of carbon dioxide and water vapor. Water vapor absorbs the heat radiated from the earth's surface. It allows less heat to escape back to space by trapping the heat energy in the lower atmosphere and keeps the atmosphere warm.
The amount of water vapor in the atmosphere is directly proportional to the temperature. When addition of the other greenhouse gases causes a temperature increase (such as extra CO2 from fossil fuels), more water evaporates and this leads to an increase in water vapor which further increases the atmospheric temperature since water vapor is a greenhouse gas. So, water vapor is part of a positive feedback system.
 
        
             
        
        
        
Answer:
cell wall
Explanation:
if its not one of the options sorry!
 
        
             
        
        
        
A Muscle Contraction Is Triggered When an Action Potential Travels Along the Nerves to the Muscles. Muscle contraction begins when the nervous system generates a signal. The signal, an impulse called an action potential, travels through a type of nerve cell called a motor neuron.