Indicate Whether Each of the Following Descriptions Better Matches the Outer

Short Answer

Indicate whether each of the following descriptions better matches the outer mitochondrial membrane (O), the intermembrane space (S), the crista membrane portion of the inner mitochondrial membrane (I), or the matrix (M). Your answer would be a four-letter string composed of letters O, S, I, and M only, e.g. OMIM.
( ) It is where NADH is produced.
( ) It is composed of 75% protein by weight.
( ) It is where the respiratory chain is located.
( ) It has the same electrochemical potential for H? as the cytoplasm.