How are I/O timeout and Safety I/O timeout calculated?

How are I/O timeout and Safety I/O timeout calculated?

A.
An I/O connection will timeout based on the lower of 4x RPI or 100ms. Safety I/O timeout is calculated as 4xRPI.

B.
An I/O connection will timeout based on the lower of 3x RPI or 100ms. Safety I/O timeout is calculated as 3xRPI.

C.
An I/O connection will timeout based on the lower of 4x RPI or 150ms. Safety I/O timeout is calculated as 2xRPI.

D.
An I/O connection will timeout based on the lower of 3x RPI or 150ms. Safety I/O timeout is calculated as 3xRPI.