A zero rate of Inflation obtains necessarily in a year where the annual rate of inflation ........

Economic Affairs Inflation

A zero rate of Inflation obtains necessarily in a year where the annual rate of inflation

in every week of the year is zero

is falling in every week of the year

is both falling and rising in a year

is constant in every week of the year

Zero sum = Fall and rise in equal proportion.

A zero rate of Inflation obtains necessarily in a year where the annual rate of inflation is both falling and rising in a year.
Unexpected inflation tends to hurt those whose money received—in terms of wages and interest payments—does not rise with inflation.
Inflation can help those who owe money that can be paid back in less valuable, inflated dollars.
Low rates of inflation have relatively little economic impact over the short term. Over the medium and the long term, however, even low rates of inflation can complicate future planning.
High rates of inflation can muddle price signals in the short term and prevent market forces from operating efficiently.

Hence option 3rd is correct.