Final answer:
The two transportable bridges used by Seabees are the Bailey and Mabey bridges, which are essential for rapid deployment in military operations.
Step-by-step explanation:
The two types of transportable bridges employed by Seabees are Bailey and Mabey bridges. These bridges are designed for military use and can be quickly assembled and disassembled, making them essential in warfare scenarios where mobility and time efficiency are critical. The Bailey bridge is a type of portable, pre-fabricated, truss bridge, while the Mabey bridge is a modular panel bridge designed for rapid deployment.