challenge: What is the systematic name of the enzyme N-acetyl-beta-glucosaminyl-glycoprotein 4-beta-N-acetylgalactosaminyltransferase?
  
  A. UDP-N-acetyl-D-glucosamine:N-acetyl-D-galactosaminyl-group beta-1,4-N-acetylgalactosaminyltransferase
  B. UDP-N-acetyl-D-galactosamine:N-acetyl-alpha-D-glucosaminyl-group 4-beta-N-acetylgalactosaminyltransferase
  C. UDP-N-acetyl-D-glucosamine:N-acetyl-beta-D-galactosaminyl-group 4-beta-N-acetylgalactosaminyltransferase
  D. UDP-N-acetyl-D-galactosamine:N-acetyl-beta-D-glucosaminyl-group 4-beta-N-acetylgalactosaminyltransferase
  Answer: 