Step 1: Understanding the Concept
Hisardale was developed by mating Bikaneri ewes with Merino rams, which are different breeds.
Step 2: The method
Mating superior males of one breed with superior females of another breed to combine desirable traits is cross-breeding.
Step 3: Compare the options
Inbreeding and out-crossing are within one breed, and no mutagen was used.
Final Answer:
Hisardale was formed by cross breeding.
\[ \boxed{\text{(B) }\text{Cross breeding}} \]