The executives cheered their CEO at the meeting when he promised to save the company from bankruptcy within 6 months. They were certain that he would fail. What is the best way to combine these sentences?

A
The executives cheered their CEO at the meeting when he promised to save the company from bankruptcy within 6 months; they were certain that he would fail.

B
They were certain that he would fail; unfortunately, the executives cheered their CEO at the meeting when he promised to save the company from bankruptcy within 6 months.

C
They were certain that he would fail, and the executives cheered their CEO at the meeting when he promised to save the company from bankruptcy within 6 months.

D
The executives cheered their CEO at the meeting when he promised to save the company from bankruptcy within 6 months; although, they were certain that he would fail.