Insert the missing phrase:

We have already suggested that a ‘‘ . . . . . . . . . . . . . . . . . . . . . . . . . ’’ approach to corporate governance structures is unrealistic, which is why most codes are both voluntary and fairly general in the way they define set standards. There is still scope to prepare best practice guides, even though they cannot be too specific.

a. substance over form

b. one size fits all

c. common or garden

d. systematic