Final answer:
Informed decision-making is a necessary element of the business judgment rule, along with acting in good faith and exercising reasonable care, while shareholder approval is not required under this rule.
Step-by-step explanation:
A necessary element of the business judgment rule is informed decision-making. This principle requires that directors make decisions with adequate information, basing their judgment on what they believe to be in the best interests of the company. In addition to informed decision-making, the business judgement rule also involves acting in good faith and exercising reasonable care, which together help to protect directors from liability as long as their actions meet these criteria. Shareholder approval is not an element of the business judgment rule, as decisions are primarily the responsibility of the company's board of directors.