flow of protons across an electrochemical gradient flow of tRNA across an electrochemical gradient exposure of ADP to electromagnetic waves exposure of carbohydrates to electromagnetic waves
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which process drives most of the ATP synthesis in a chloroplast?
Possibilities:
- flow of protons across an electrochemical gradient
- flow of tRNA across an electrochemical gradient
- exposure of ADP to electromagnetic waves
- exposure of carbohydrates to electromagnetic waves

flow of protons across an electrochemical gradient