Step 1: List the functional requirements of an injection platform:
An injection well platform on an offshore field has three broad functional requirements: it must handle the correct injection fluid, it must monitor and control the rate at which that fluid enters each well, and it must meet the same personnel safety standards as any other manned offshore structure.
Step 2: Check the fluid type against option (A):
A water injection well platform is, by definition, built around injecting water for reservoir pressure support and waterflooding, not gas. A platform meant for gas injection would be a separate facility type. So option (A) fails this check.
Step 3: Check the rate control requirement against options (B) and (C):
Injection rate control is a core reservoir management activity. Without metering devices, the operator cannot know how much water is going into each well, cannot balance injection with voidage replacement, and cannot detect problems like thief zones or plugging. This makes metering devices a necessity, so option (C) passes this check and option (B), which denies this necessity, fails.
Step 4: Check the safety requirement against option (D):
Since the platform is a manned offshore structure handling pressurized fluids, it is subject to the same safety codes as production platforms, which mandate firefighting systems and life saving equipment on board. So option (D) passes this check.
Step 5: Consolidate the results:
Only options (C) and (D) satisfy the actual functional and safety requirements of a water injection well platform, while options (A) and (B) contradict them.
Final Answer:
\[ \boxed{\text{(C) and (D) are correct}} \]