The correct option is B
a-iii, b-iv, c-i, d-ii
a) Endoplasmic reticulum (SER) are not studded with ribosomes and is responsible for the synthesis of lipids and is also involved in the production of steroid hormones.
b) Free ribosomes are the main site of non-secretory protein synthesis and are composed of ribonucleic acids and proteins.
c) Mitochondria are a double-membraned cell organelle, known as the powerhouse of the cell and responsible for cellular respiration.
d) The contractile vacuole is a sub-cellular organelle found in few protozoans which is a specialized vacuole that helps in regulating the quantity of water inside a cell (osmoregulation) and excretion.
So, the correct answer is 'a-iii, b-iv, c-i, d-ii'.