Which of these membranes is the richest in protein?

Explanation

Option B is correct since membranes are involved in ATP production (such as the internal membranes of mitochondria and chloroplasts), approximately 75% is protein. Option A is incorrect since 'The nuclear envelope is composed of the nuclear lamina, nuclear pore complexes, and nuclear membranes. Option C is incorrect since the structure of the 'endoplasmic reticulum' is a network of membranes called cisternae and the phospholipid membrane encloses the cisternal space. Option D is incorrect since a typical 'plasma membrane' is somewhere in between, with protein accounting for about 50% of its mass.