Answer and Explanation:
Observing population directly gives you accurate result .
Direct observation does not need any intermediary as they themselves go for survey.
So, it is cost efficient.
Whereas indirect observing may involve manipulations.
It requires someone or many to hire who helps in surveying.
It incurs cost.
Thus, direct observation is always better than indirect observation.
I believe the answer is A
3) decrease
Without the green house effect, earth would be like a solid ball of ice and rock.
Life as we know it wouldn't exist without greenhouse gases.
The temperature would drop below 0° Fahrenheit!
D.) none of the above is human induced cause of extinction
