Select the option that will improve the underlined part of the given sentence. In case no improvement is needed, select 'No improvement required'.

He indicated that a vigorous recovery programme was being carried out; 90,000 reminders had been issued and thousands of summons sent.

A

has been issued and thousands of summons sent

B

No improvement required

C

has been issued and thousands of summonses sent

D

had been issued and thousands of summonses were sent