Answer
(d)
Work Step by Step
Determine the annual rate of increase from $1980$ to $1990$:
$CO_2\text{ increase}=350−335=15$ ppm over $10$ years.
The annual rate is
$\text{Annual rate}=15\div 10=1.5$ ppm/year
Number of years from $1990$ to $2030$:
$2030−1990= 40$ years
Project the increase over $40$ years:
$1.5\times 40 = 60$ ppm
Add to the $1990$ concentration:
$350+60=410$ ppm
The answer is (d).
