First we need to deterine the extinction coefficient for the system at 710 and 740 nm. At the highest [HCl] the solution is essentially all [CoCl4]-2, the [Co(H2O)6]+2 can ignored. What is the extenction coefficient for 740 nm?

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later

Solubility would be your answer.

Sorry i think the answer is b