Hi, lsatstudy and lalalala!
Good questions!
lalalala:
(P---N)
(P---T) changes the game. P can be older than N (P----N) independently of P being older than T (P---T).
If we were to substitute the rule in answer choice (E) we'd end up in a situation in which P couldn't be older than N and older than T at the same time. This is not true of the game in either of the either/or scenarios related to the last rule (the P, H,N dual option rule).
Further, where's J in all this? It's just floating around and could very well be newer than T. Answer choice (E) both disrupts something else in the game and doesn't replace one of the parameters of the rule we are substituting.
lsatstudy:
Nikki does an excellent job addressing answer choice (B) in an explanation earlier in this thread:
viewtopic.php?p=8852#p8852
Kelsey does a great job explaining answer choice (C) in her explanation:
viewtopic.php?p=71033#p71033
You're right that rule substitution questions are not the same as finding a rule that if implemented would fully determine the assignment of variables.
The task is to find a rule that, if substituted for one of the existing rules, would make the game operate in precisely the same way. You remove a rule and then swap something in to make the game work the way it originally did. You must replace all the restrictions of the original rule without adding new restrictions.
In the Lesson 7 homework to the PowerScore course, there's a complete breakdown of how to attack rule substitution questions.
In chapter 9 of the
Logic Games Bible, there's a complete breakdown of strategy for these questions.
I hope this helps!