Which of the following is the correct syntax for including a schema file in slapd.conf?

Which of the following is the correct syntax for including a schema file in slapd.conf?

A.
include /usr/local/etc/openldap/schema/core.schema

B.
add /usr/local/etc/openldap/schema/core.schema

C.
permit /usr/local/etc/openldap/schema/core.schema

D.
allow /usr/local/etc/openldap/schema/core.schema