12. An unknown mixture of 5 amino acids gives the following IEF pattern:
The 5 amino acids could be:
a) tyrosine, methionine, serine, histidine and lysine
b) methionine, valine, histidine, proline and lysine
c) methionine, serine, valine, leucine and lysine
d) methionine, serine, valine, histidine and lysine
