Answer : 4. "For all of these"
Explanation :

The opaque-2 mutation in maize (Zea mays) is associated with increased levels of free amino acids (FAA) in mature endosperm. In particular, it contains a high concentration of lysine, the most limiting essential amino acid. To investigate the basis of the high-FAA phenotype of opaque-2 maize, we characterized amino acid accumulation during endosperm development of several wild-type and opaque-2 inbreds.