In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.

The saving of certain wild animals from extinction (1)_____ many years been a problem for the zoologists and other specialists; but more recently the problem has become so (2)_____, and has received so much publicity, that most people are now (3)_______ about it. This may at first seem strange because one of the most gratifying developments of the last few years has been the passing of strict laws to protect wild animals and the (4)_________ decline in the hunting of big-game for sport. Why is it then that some rare wild animals are still (5)________ with extinction and even some of the less rare ones are rapidly declining in number?