FULLTEXT indexes can be created only for . . . . . . . .

In MySQL, FULLTEXT indexes can be created only for tables that use the MyISAM storage engine.
FULLTEXT indexes allow for efficient searching of text data, enabling full-text search capabilities in MySQL.
The InnoDB storage engine, represented by Option B, does not support FULLTEXT indexes natively in MySQL. However, in recent versions, InnoDB has introduced support for FULLTEXT indexes with some limitations.
Options C and D (MEMORY and TRANSITION) are incorrect because neither of these storage engines supports FULLTEXT indexes in MySQL.