Which accounting standard is followed in UK and USA ?

USA uses US GAAP.

UK uses IFRS

in USA its GAAP

in UK its IFRS's

The answer is redundant because they are already listed and said ....

UK follows IFRSs

USA follows GAAPs

uk is using the IFRS while u.s. is following GAAP  standards..

With respect to UK it is International Financial Reporting standards, with respect to US, the standards known as Federal Accounting Standards (FAS - Bare standards) and their codification Federal Accounting Standard Board (FASB - codified version). These standards are covered under US Generally accepted accounting practices - US GAAP.