marginal rate of tax

Q- Matt’s net income for the tax year 2022-2023 was 116000.
what is the highest effective marginal rate of income tax that matt will suffer in the tax year 2022-2023?
a- 40%
b-45%
c-50%
d-60%

————doubt————
the answer is d but I’m not understanding the explanation. well the first half i got it that the income is in 40% tax rate. but i’m not understanding how the reduction of personal allowance will increase the marginal rate of income tax.
please if possible explain it by calculation.

thankyou