Which of the following is a Enrichment broth: (A) Selenite F broth, (B) Blood agar, (C) Loeffler's serum slope, (D) All the above
Answer is A. Enrichment media is liquid media that allow certain organism to grow and inhibit others.
Example:

Selenite F broth and Tetrathionate broth for salmonella & Shigella.
Alkaline peptone water for Vibro cholerae.