Final answer:
When light strikes chlorophyll molecules, the lost electrons are replaced by electrons obtained from the splitting of water, a process facilitated by light and involving photolysis. So, the correct answer is the fourth option.
Step-by-step explanation:
When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by splitting water. The process begins when a photon of light energy hits the chlorophyll, exciting an electron to a higher energy state. This 'excited' electron is captured by a primary electron acceptor to participate in further reactions.
To replenish the electron deficit in the chlorophyll, a molecule of water is split through a process called photolysis, which occurs in the presence of light. This split results in the formation of oxygen (O₂), hydrogen ions (H+), and new electrons. The electrons released from this process then replace those that were lost from chlorophyll, allowing it to capture more photons and continue the photosynthetic process.
So, the correct answer is the fourth option.