Match List - I with List - II and choose the correct answer.

List - I	List - II
(a) Cristae	(i) Primary constriction in chromosome
(b) Thylakoids	(ii) Disc-shaped sacs in Glogi apparatus
(c) Centromere	(iii) Infoldings in mitochondria
(d) Cisternae	(iv) Flattened membranous sacs in stroma of plastids

The correct option is a - (iii) b - (iv) c - (i) d - (ii).

Let us analyze and match the cellular structures in List - I with their correct functions or descriptions in List - II step-by-step:

(a) Cristae:
Cristae are the inner infoldings of the inner mitochondrial membrane. They increase the surface area available for chemical reactions, such as cellular respiration and ATP synthesis.
Hence, (a) matches with (iii) Infoldings in mitochondria.

(b) Thylakoids:
Thylakoids are flattened, membranous sacs found within the stroma of chloroplasts (plastids). They contain chlorophyll and are the site where light-dependent reactions of photosynthesis occur.
Hence, (b) matches with (iv) Flattened membranous sacs in stroma of plastids.

(c) Centromere:
The centromere is the primary constriction region in a chromosome. It holds sister chromatids together and serves as the site for spindle fiber attachment during cell division.
Hence, (c) matches with (i) Primary constriction in chromosome.

(d) Cisternae:
Cisternae are flattened, disc-shaped membranous sacs or vesicles stacked together in the Golgi apparatus. They are involved in modifying, sorting, and packaging proteins.
Hence, (d) matches with (ii) Disc-shaped sacs in Golgi apparatus.

Combining these individual matches gives:
a - (iii), b - (iv), c - (i), d - (ii)