Step 1: Recall the three lists.
The Seventh Schedule distributes subjects among the Union List, State List, and Concurrent List. On concurrent subjects, both Union and States can legislate; Union law prevails on conflict (Art. 254).
Step 2: Original vs present count.
Originally (1950) the Concurrent List had 47 entries. The 42nd Amendment (1976) shifted several items from the State List and expanded the Concurrent List to 52 entries (current standard count).
Step 3: Conclude.
\[
\boxed{\text{Concurrent List has 52 subjects (Option B).}}
\]