Sentence Correction

Internet executives say online advertising takes in more than $20 billion a year if advertisers had reliable and consistent ways to measure online users' potential interest in specific products and services.

A. Internet executives say online advertising takes in more than $20 billion a year if
B. According to Internet executives, online advertising would take in more than $20 billion a year and if
C. Internet executives say that online advertising would take in more than $20 billion a year if
D. Online advertising according to Internet executives could take in more than $20 billion a year depending on
E. Online advertising, Internet executives say, has taken in more than $20 billion a year provided that


Pls let's have some discussions before i post the OA. Thanks.

The use of IF + the Past Simple form "had" indicates that we need to use Conditional 2.

IMO - C If+ Simple Past should go with Would... Whats the OA .

Use of had in non-underlined part suggests that would is required here.
IMO C

C
WOULD + HAD 'PAST TENSE'