The following are the statements about non-chordates:

A. Pharynx is perforated by gill slits.

B. Notochord is absent.

C. Central nervous system is dorsal.

D. Heart is dorsal if present.

E. Post anal tail is absent.

Choose the most appropriate answer from the options given below:

The correct option is B, D & E only.

To identify the correct statements about non-chordates, let us compare the key anatomical differences between chordates and non-chordates:
1. Notochord: In chordates, a notochord is present during embryonic development or throughout life. In non-chordates, a notochord is completely absent. Therefore, statement B ("Notochord is absent") is correct.
2. Pharynx and Gill Slits: The pharynx of chordates is perforated by gill slits for respiration. In non-chordates, pharyngeal gill slits are absent. Therefore, statement A is incorrect.
3. Central Nervous System (CNS): In chordates, the central nervous system is dorsal, hollow, and single. In non-chordates, the central nervous system is ventral, solid, and double. Therefore, statement C ("Central nervous system is dorsal") is incorrect.
4. Heart: In chordates, the heart is located ventrally. In non-chordates, the heart is positioned dorsally (if it is present). Therefore, statement D ("Heart is dorsal if present") is correct.
5. Post-anal Tail: A post-anal tail is typically present in chordates at some stage of life. In non-chordates, a post-anal tail is absent. Therefore, statement E ("Post anal tail is absent") is correct.

By analyzing the statements:
- Statement A: Incorrect for non-chordates
- Statement B: Correct for non-chordates
- Statement C: Incorrect for non-chordates
- Statement D: Correct for non-chordates
- Statement E: Correct for non-chordates

Thus, statements B, D, and E are the only correct statements regarding non-chordates.