Please answer the following question: Read the following article and select the best answer. Article: You never forget your first whale. The impact it makes upon you is huge and life is never quite the same again. My first whale was a 40ft grey, off the coast of California in 1979, and I've been a whale addict ever since. Now I have to go whale watching regularly just to survive normal daily life. I may be crazy but I am certainly not alone. The world is filled with whale watchers: since its beginnings in the mid-fifties, whale watching has grown dramatically and now more than 13 million people join organized whale watching trips every year. As a faithful whale watcher, all your holidays center on whales. The only books you read are ones about whales; you wear whale T-shirts, and every time you meet your friends you talk about whales. So what is it about these larger-than-life animals that makes them so special? Their enormous size is one possible explanation: imagine sitting in a small boat next to a blue whale almost as long as a Boeing 737.The fact that we know so little about them is another possibility: modern technology has taken us to the moon and beyond, yet we are only just beginning to understand these extraordinary forms of intelligent life on our own planet. Planning and patience are just two essential requirements for successful whale watching. Planning is needed because there are certain whale hot spots--where you have the best chance of seeing them--and because the larger species tend to be on their way from feeding areas to breeding grounds, so rarely do they stay in one place for more than a few months at a time. Patience is necessary because, even under the best conditions, whales can be tricky to find. However, most commercial whale watching trips have a surprisingly high success rate because they tend to concentrate on well-known whale populations at peak seasons. Question: Why is patience necessary in whale watching? - Because it is very difficult to find these clever whales. - Because whales are on their way to breeding grounds. - Because the watching conditions are not always good. - Because they have enormous size as big as a Boeing plane.
A:
Because it is very difficult to find these clever whales.