Theory because a theory is a well substantiated explanation of how a particular phenomenon works based on the set of facts which had been repeatedly confirmed through observations and experiments. A scientific theory gives reliable account of a phenomenon.
There are around 350,000-600,000
I would go for 'c'. The reason being, is that it doesn't do much, and I am also assuming that offshore drilling will not affect underwater sources, which are linked to the ocean.
Technically, the black widow spider is the deadliest spider despite it's size, due to it's overwhelmingly potent venom, which can and will kill a human if no medical attention is sought out for the person bit.
