Cost is a factor when considering Biometrics but it is not a security characteristic.
All the other answers are incorrect because they are security characteristics related to Biometrics.
data acquisition process can cause a security concern because if the process is not fast and efficient it can discourage individuals from using the process.
enrollment process can cause a security concern because the enrollment process has to be quick and efficient. This process captures data for authentication.
speed and user interface can cause a security concern because this also impacts the users acceptance rate of biometrics. If they are not comfortable with the interface and speed they might sabotage the devices or otherwise attempt to circumvent them.
References: OIG Access Control (Biometrics) (pgs 165-167)
From: TIPTON, Harold F. & KRAUSE, MICKI, Information Security Management Handbook, 4th Edition, Volume 1, Pages 5-6. in process of correction