Which understanding of this ratio is correct?

You work as a DBA and you have the responsibility of managing a large online transaction
processing (OLTP) system. You used the following query during the performance tuning activity:
SQL> SELECT (1-((phy.value-phyd.value) / (cur.value + con.value))) * 100
2 “Cache Hit ratio”
3 FROM v$sysstat cur, v$sysstat con, v$sysstat phy, v$sysstat phyd
4 WHERE cur.name = ‘db block gets’
5 AND con.name = ‘consistent gets’
6 AND phy.name = ‘physical reads’
7 AND phyd.name = ‘physical reads direct’;
Cache Hit Ratio
—————
98.43

Which understanding of this ratio is correct?

A.
98.43% of times the requests have found free buffers.

B.
98.43% of the total number of requests used the buffer cache.

C.
98.43% of times the requests were satisfied by performing physicalI/Os.

D.
98.43% of times the requests have found the required data blocks in the buffer cache.