Which food source provides the highest quality protein (biological value)?

Correct option is B

Egg protein is considered the gold standard (biological value = 100). Soy and milk have high protein but slightly lower biological value.
Explanation of options: (a) ✘ Soybean has highest plant protein, but lower than egg. (b) ✔ Correct; egg protein = reference protein with BV 100. (c) ✘ Milk is high quality but BV < egg. (d) ✘ Wheat protein is poor in lysine, low quality.