A web application requires knowledge of the client’s true IP address for logging and analysis purposes.
Instances of the application that can decode X-Forwarded-For HTTP headers reside in pool_a, while pool_b
instances assume the source IP is the true address of the client.
Which iRule provides the proper functionality?

A.
when HTTP_DATA {
if {[HTTP::header exists X-Forwarded-For]}{
pool pool_a
} else {
pool pool_b
}
}

B.
when HTTP_RESPONSE {
if {[HTTP::header exists X-Forwarded-For]}{
pool pool_a
} else {
pool pool_b
}
}

C.
when HTTP_REQUEST {
if {[HTTP::header exists X-Forwarded-For]}{
pool pool_a
} else {
pool pool_b
}
}

D.
when HTTP_OPEN {
if {[HTTP::header exists X-Forwarded-For]}{pool pool_a
} else {
pool pool_b
}
}