Why opening inventory doesn’t belong to P/L

Hello,

The answer for the 1st task of the test # 19.3 in F3 (FA) BPP Revision Kit 2020 states that the opening inventory of the financial year does not belong to P/L. However, F3 (FA) BPP Study Text 2020 states otherwise in Chapter 7 – 2.2 Ledger accounting for inventories – page 115:

“As it happens, the $1,800
closing inventory was the only entry in the inventory account – there was no figure for opening inventory.
If there had been, it would have been eliminated by transferring it as a debit balance to the income and
expenditure account, ie:
DEBIT P/L account (with value of opening inventory)
CREDIT Inventory account (with value of opening inventory)
The debit in the profit or loss account would then have increased the cost of sales, ie opening inventory
is added to purchases in calculating cost of sales.”

Please help me understand why there is no contradiction between the test an the study text.