Several people should be trying to teach the bird to talk

Each of the following is a potential effect of a low dose of radiation EXCEPT one. Which one is the EXCEPTION?

a. No cell response. b. Cell repairs itself and functions at pre-exposure levels. c. Cell repairs itself abnormally. d. Cell becomes radioactive.

An inherited form of anemia in which a defective hemoglobin chain causes microcytic, hypochromic, short-lived red blood cells is ________. 

Fill in the blank(s) with the appropriate word(s).