The answer is B. This is called genetic shift. The pups with
advantageous traits are able to survive until the age of reproduction hence able
to pass their genes to the next generation. Few and fewer pups with disadvantageous
traits will get to reproduce hence the allelic frequencies of the shark population
will shift in favour of increased hunting efficiency.
Well, many organisms would die. Plants need light so they would die out rather quickly. The surrounding area would warm up initially due to the green house effect, but would eventually cool down.
After a quick search, I was able to find a source with your question and its multiple choice answers
Next time, you should include them, it is helpful!
"Which describes the action of a ligand's competitive antagonist?"
-A.) It decreases the amount of ligand required to activate the protein.
-B.) It blocks the binding of the ligand to its binding site and prevents activation of the protein.
-C.) It binds to a different binding site on the protein, altering the protein shape so that a ligand cannot bind.
D.) When present, it increases the binding of a ligand to its receptor.
Your answer would be "B".