Items and percentages

Sorry for the noob post, one thing I'm wondering is how Item's with an increase in stat by percentage work?

For instance,

Torch Bearer has 3.63 base mana regen right?

the Plenor Battlecrown gives 70% Mana Regen

so combined that's 3.63 * 1.7 = 6.171 mana regen is that correct?

How about if another absolute mana regen is introduced, say, All Fathers ring that has 25 mana regen

does that combine to

A: (3.63 + 25) * 1.7 = 48.671

or

B: (3.63 * 1.7) + 25 = 31.171

or C: something I haven't thought of?

Lastly, how about combining multiple relative regens such as TB + Plenor Battlecrown + Vinling Helmet

is that

A: 3.63 * 1.7 * 1.7 = 10.49 //both items give 70% increase

B: 3.63 * 2.4 = 8.712 //both items percentage adds to give 140% increase

or 

C: something I've missed once again!

Thaaaaaaaanks