In Determining the Firm's Target Cash Balance,trading Costs

In determining the firm's target cash balance,trading costs:

A) tend to fall when cash balances are large.
B) tend to rise when cash balances are large.
C) tend to rise when cash balances are low.
D) Both tend to fall when cash balances are large; and tend to rise when cash balances are large.
E) Both tend to fall when cash balances are large; and tend to rise when cash balances are low.