This question focuses on the demographic implications of the change in male mortality rates. The correct answer is 'C' because the passage states that there will be an excess of boys in the crucial years when they are searching for a mate. Option 'A' is incorrect because the passage suggests an excess of males, not females. Option 'B' is incorrect because the passage indicates an increase, not a decrease, in the number of males. Option 'D' is incorrect because the passage implies a change in the ratio, not that it will remain the same.