The treaty specifies that the economy of the member nations

[BTGmoderatorDC]

The treaty specifies that the economy of the member nations have inflation rates of less than three percent and resist external tariffs.

(A) economy of the member nations have inflation rates of less than three percent and resist
(B) economy of each member nation have an inflation rate of less than three percent and be resistant to
(C) every economy of the member nations have an inflation rate of less than three percent and be resistant to
(D) economies of each member nation have inflation rates of three percent or less and are resistant to
(E) economies of every member nation have three percent or less of an inflation rate and resist

OA B

Source: Princeton Review

[coxy4972]

Can anyone help explain the answer to this one?

(A) economy of the member nations have inflation rates of less than three percent and resist
(B) economy of each member nation have an inflation rate of less than three percent and be resistant to
(C) every economy of the member nations have an inflation rate of less than three percent and be resistant to
(D) economies of each member nation have inflation rates of three percent or less and are resistant to
(E) economies of every member nation have three percent or less of an inflation rate and resist

I can't quite understand why it is ".... the economy of each member nation have" and not "...the economy of each member nation has." If we are dealing with a singular noun 'the economy,' why is the verb in the plural form 'have' in the correct answer and not the singular 'has'?

What rule am i missing here?