Find the correctly matched pair without any exceptions

To find the correctly matched pair without any exceptions, let us analyze each of the options in detail:

1. Reptilia - 3 chambered heart with undivided ventricle:
Most reptiles have a 3-chambered heart with an incomplete partition (divided ventricle). However, there is a prominent exception: crocodiles, which belong to the class Reptilia, possess a fully 4-chambered heart with completely divided ventricles. Therefore, this match has exceptions and is incorrect.

2. Chondrichthyes - cartilaginous endoskeleton:
The class Chondrichthyes consists of cartilaginous fishes (such as sharks, rays, and skates). One of the defining characteristics of this entire group is that their endoskeleton is made entirely of cartilage, and this feature is present in all members without exception. Therefore, this is a correctly matched pair without any exceptions.

3. Mammalia - viviparous:
While the vast majority of mammals give birth to live young (viviparous), there are notable exceptions. The monotremes, such as the duck-billed platypus (Ornithorhynchus) and echidna (spiny anteater), are egg-laying mammals (oviparous). Hence, this option contains exceptions and is incorrect.

4. Chordata - have mouth with a lower and upper jaw:
The phylum Chordata includes both jawed vertebrates (Gnathostomata) and jawless organisms (Agnatha, such as lampreys and hagfishes) which lack upper and lower jaws. Therefore, having a mouth with a lower and upper jaw is not a universal characteristic of all chordates, making this match incorrect.

Thus, the only pair matched correctly without any exceptions is Chondrichthyes with a cartilaginous endoskeleton.