Answer: Option 'b' is correct.
Step-by-step explanation:
Since we have given that
Total number of birds = 14000
Let the number of birds on X be 'x'.
Let the number of birds on y be 14000-x
After one year, 20 percent of the birds on X have migrated to Y, and 15 percent of the birds on Y have migrated to X.
but The number of birds on each of the islands X and Y remains constant from year to year.
So, the equation would be
[tex]\dfrac{20}{100}x=\dfrac{15}{100}(14000-x)\\\\0.2x=0.15(14000-x)\\\\0.2x=2100-0.15x\\\\0.20x+0.15x=2100\\\\0.35x=2100\\\\x=\dfrac{2100}{0.35}=6000[/tex]
Hence, there are 6000 birds on island X.
Hence, Option 'b' is correct.