(a) In granting any proxy, reasonable care must be exercised in deciding who shall act as proxy and whether or not instructions as to the voting of said stock shall be given to such proxy.
(b) If there are two or more fiduciaries acting, the proxy shall be executed by, and voting instructions shall be issued by, agreement of all fiduciaries or a majority of them.
(c) In the event the manner or method of voting, or the purposes to be accomplished, are fixed by the instrument or instruments appointing said fiduciaries, the directions contained therein shall govern.