West will pass.

North will then open. In Acol North is not strong enough for 2♣ . So the choice is to bid 2N showing 20-22 with a singleton. This is allowed by EBU and opening a 2N or 2♣  followed by 2NT. However if you open 1NT with a singleton this should be announced online or alerted by your partner in f2f.

The alternative is to bid 1♣  and rebid ♥ s to show the unbalanced shape.

Over 1♣  East will make life difficult with a preemptive 3♠ 

South is not strong enough to double.

West will pass.

North will double for Take Out.

South will bid 4♥ s for the optimum contract.

Over 2NT (accepting it is off shape) East may try a risky 3♠ .

If so South knows they have 26+HCPs and will double (for TO?)

North will bid 4♥ s for the optimum contract.

If East manages to play 3♠ though the double dummy says minus 2. The likely result is -1 unless south can lead ♣ s early, either on lead, though a ♠ lead will be made by many, then North hsa to lead a ♦ (low one for a ♣ swith) and hopefully South finds the ♣ lead.

If East passes over 2NT stayman will find the 4♥ contract.

With Benji openings  North opened 2♣ (21-22 HCPs or 8 Playing Tricks). On playing tricks North is well short of 8 Playing Tricks and only relies on the offshape NT.

A reminder for Playing Tricks.

For relatively strong hands containing long suits (e.g. an Acol 2 opener), playing tricks are defined as the number of tricks expected, with no help from partner, given that the longest suit is trumps. Thus for long suits the ace, king and queen are counted together with all cards in excess of 3 in the suit; for short suits only clear winner combinations are counted:

A = 1, AK = 2, AKQ = 3
KQ = 1, KQJ = 2
An Acol strong 2 of a suit opening bid is made on 8 playing tricks (Landy 1998)

So North's hand has A, AK, and KJ = 0.5 the AQ =1.5 a total of 5 (maybe 5.5 if you count AQ 10 as 2)