When does a light wave refract

Group of genes that encode molecules found in all body cells, creating a biochemical “fingerprint” that serves as the “id” for cells so that they are marked as “self” a) deoxyribonucleic acid (dna) b) entry inhibitors c) major histocompatibility complex (mhc) d) non-nucleoside reverse transcription inhibitors (nnrtis)

Minor illnesses: a.) decrease the risk of sids b.) increase the risk of sids c.) increase the risk of hospitalization d.) decrease the risk of allergies e.) increase the risk of allergies

Can someone give me a hand with this one.