Step 1: Recall the relationship between recombination frequency and map distance.
Genetic distance is measured in centimorgans (cM).
\[
\boxed{
1\% \text{ recombination } = 1 \text{ centimorgan}.
}
\]
Step 2: Calculate the map distance.
Given,
\[
\text{Crossing over}=10\%.
\]
Hence,
\[
\boxed{
10\%=10\text{ cM}.
}
\]
Therefore,
\[
\boxed{10\text{ centimorgans}}
\]
is the correct answer.
Thus,
\[
\boxed{(B)}
\]
is the correct answer.