Identify the comma error(s) in the following sentences and choose the best revision.

Since many executives have access to company jets boards of directors have a responsibility to ensure, that shareholders are not footing the bill for personal travel.
Since many executives have access to company jets, boards of directors have a responsibility to ensure, that shareholders are not footing the bill for personal travel.
Since many executives have access to company jets, boards of directors have a responsibility to ensure that shareholders are not footing the bill for personal travel.

Since many executives have access to company jets, boards of directors have a responsibility to ensure that, shareholders are not footing the bill for personal travel.

Explanation: Comma , is a symbol that separates parts of a sentence or single things in a sentence.

There is little or no explanation to give here. In the first two sentences the comma was wrongly placed.

In the third sentence, the comma was cited properly, which is the sentence above.