To solve this problem, we need to identify the method used to form the new breed 'Hisardale' of sheep by using Bikaneri ewes and Marino rams.$\newline$Let's analyze the options:$\newline \bullet$Mutational breeding:$\newline$ - This involves inducing mutations to create genetic variations. It is not typically used for forming new breeds by combining existing breeds.$\newline \bullet$Cross breeding:$\newline$ - This involves mating individuals from two different breeds to produce offspring with desirable traits from both.$\newline$ - In this case, Bikaneri ewes and Marino rams are two different breeds, and their combination to form 'Hisardale' is an example of cross breeding.$\newline \bullet$Inbreeding:$\newline$ - This involves breeding individuals within the same breed to maintain or enhance specific traits. It is not applicable here as it does not involve different breeds.$\newline \bullet$Out crossing:$\newline$ - This involves breeding individuals from the same breed but with no common ancestors for several generations. It is not applicable here as it does not involve different breeds.$\newline$Based on the analysis, the correct method used to form the 'Hisardale' breed is cross breeding.$\newline$Therefore, the correct option is Option 2: Cross breeding.