Extent of natural cross-pollination and the desired isolation distance are given. Find out the wrong one.

Answer: Option D

Isolation distance is the minimum separation required between two or more varieties of the same species for the purpose of keeping seed pure.
As a general rule, plants that primarily self-pollinate require less isolation distance, while plants that primarily cross-pollinate require greater distances.
Therefore None of the above options given is wrong as per the rule, that is the extent of natural cross-pollination is decreasing with decrease in distance.
When isolation distance is more that is 500 - 1000 meter, the extent of natural cross-pollination is maximum i.e. 50 - 75%.