I'd say it's (c) for sure, and think it generally makes a lot of sense. You'd only need to be converting a kick for the corner into a try about 50% of the time to be better off not taking the 3. You also generally get more than 1 shot to convert a kick for the corner with opposition teams infringing, increase your chances of the opposition getting carded and converting territory into as many points as possible. Except when conditions are tough, your lineout isn't working or it's towards the end of the game and 3 guaranteed points are what is required, I think it's what all teams should generally be doing.
| Probability of Success | Points | Effective Points |
Kick for Corner | 50% | 6.5 | 3.25 |
Penalty Kick | 90% | 3 | 2.7 |