What defines a steer?

The correct answer is defined by the specific characteristics of a steer in livestock terminology. A steer is indeed a male bovine that has been castrated, which means it cannot reproduce. This procedure is commonly performed to improve the animal's temperament and manageability, making it easier for handlers and farmers to work with. Castration also encourages better growth and fat deposition in the animal, making steers highly valued in beef production.

In contrast, the other options are distinct types of livestock unrelated to the definition of a steer. A female sheep is referred to as a ewe, a female goat is known as a nanny or doe, and a young calf is simply a term for a young bovine, which can include both male calves and female calves. Therefore, the identification of a steer specifically as a male bovine that has been castrated places it correctly in the livestock classification system.