Refer the given statements -

(i) Incomplete or mosaic inheritance is an example of the pre-Mendelian concept of blending inheritance.
(ii) A test cross is a special type of back cross.
(iii) Chromosomal aberrations are commonly observed in cancer cells.
(iv) Thalassaemia is a Mendelian disorder.

Which of the above statements are correct?

The correct option is C (ii), (iii) and (iv)

• Incomplete (partial or mosaic) dominance is the phenomenon where none of the two contrasting alleles or factors is dominant. The expression of the character in a hybrid or $F_1$ individual is intermediate or a fine mixture of the expression of the two factors (as found in the homozygous state). Incomplete or mosaic inheritance is not an example of the pre-Mendelian concept of blending inheritance because the parental types reappear in the $F_2$ generation. So, this statement is incorrect.