18. The effect of various mutations in a gene x coding for a protein X, essential for the synthesis of leucine, is studied in a haploid yeast. The beginning and the end of the complete sequence of the coding strand of x is given below. Indicate the following statement is true. (A) Cells with a CT mutation at position 13 produce shorter mRNA of x (B) Cells with a AT mutation at position 37 produce shorter version of X (C) Cells with a AT mutation at position 16 are able to grow on a medium lacking leucine. (D) Cells with an additional G between positions 33 and 34 produce functional X.