What is the optimal LET value in producing biologic effect? And explain why the RBE curve peaks at this optimal value? What is the reason behind the drop in the RBE curve after optimal value of the LET?

Cells a and b are the same size and shape, but cell a is metabolically quiet and cell b is actively consuming oxygen. oxygen will diffuse more quickly into cell because . b the oxygen molecules inside cell b have a higher kinetic energy b. a its membrane transport proteins will not be saturated c. a the diffusion gradient there is shallowerd. b the diffusion gradient there is steeper