The verb is past participle so that would be option A.
A barbecue?
Men use Barbecues a lot and I guess they could go inside too.
Answer:
b. It’s certain that they were man-made.
Answer:
What force causes phenomena?
Forces can be described as a push or pull on an object. They can be due to phenomena such as gravity, magnetism, or anything that might cause a mass to accelerate. In physics, a force is any interaction that, when unopposed, will change the motion of an object.
Explanation:
which is the write by your self