The Gold Key Service, a custom$-$tailored service offered US companies seeking to visit a foreign market for business, that combines market research, assistance in developing a marketing strategy, orientation briefings, introduction to potential partners, interpreters and more is offered by which of the below government agencies a$)$ International Trade Administration b$)$ US Customs and Border Protection c$)$ Foreign Service and embassies US Department of State d$)$ Commercial Service of the US Department of Commerce