The principles and standards of ethical supply chain management conduct includes the principle:
a) promote competitive relationships with suppliers.
b) social competence.
c) protect confidentiality.
d) be true to yourself.

D) Be true to yourself.

Explanation:

The Institute of management have about 10 standards for supply management conducts. these standards are derived from 3 major principles which are;

Integrity in Your Decisions and Actions

Value for Your Employer

Loyalty to Your Profession.

The 10 standards are; Impropriety, conflict of interest, influence, responsibility to your employer, supplier and customer relationship, sustainability and social responsibility , reciprocity, confidential and proprietary information , professional competence and applicable laws, regulations and trade agreements .

there is no mention of be true to yourself.

"harry t. moore (1905-1951) – civil rights activist, leader, and the first martyr of the civil rights movement. fannie lou hamer (1917–1977) – leader in the american civil rights movement; co-founder of the national women's political caucus and freedom democratic party. james farmer (1920–1999) – congress of racial equality."