In most corporations, strategy$-$making is

more of a collaborative group effort that involves executives and managers at many organizational levels, as opposed to being the function and sole responsibility of a few high$-$ranking executives.

primarily the joint responsibility of a company's senior executives and board of directors.

first and foremost the function and responsibility of a company's chief strategy officer $($who usually reports directly to the chief executive officer and also coordinates closely with members of the company's board of directors$).$

first and foremost the function and responsibility of a company's board of directors.

first and foremost the function of a company's chief executive officer $-$ who formulates strategic initiatives and submits them to the board of directors for approval.