Which of the following checks dna for errors?

Ineed to know why d is the correct answer asap

Plz genetic engineering can be applied to many fields including medicine and agriculture. which of the following is a medical application of genetic engineering? a. giving crop plants recombinant dna so that they would be resistant to herbicides. b. examining a persons pedigree to determine whether they can carry a gene for a genetic disease. c. analyzing a persons dna to see how closely they are related to another person. d. certain genes into bacteria so that they will produce a needed medicine.

The terrestrial planets are characterized by having a a.) silicate core b.) iron-rich silicate core c.) iron-rich metallic core d.) none of these