Police countable or uncountable?

[Giulia]

Test No. errors/inter-1 "Save money now", question 6

The police in that country does not carry guns when they are in the street.

(a) does
(b) carry
(c) they
(d) street

Test No. errors/inter-1 "Save money now", answer 6

The police in that country do not carry guns when they are in the street.

Correct entry: do
The error was: (a) does
_________________________

Why you have "the" (singular) and then "do" and "they"(plural)?

[Mister Micawber]

The is not exclusively singular; it is used for both numbers:

The ant under my shoe is dead.
The ants under my shoe are dead.
_________________
Native English teacher at Mister Micawber's