The beef isn't a sustainable choise, because producing it produces CO2 and methane, which are one of the most damaging green house gasses.

Moreover, the animals often have bad conditions in their shelter and the meat doesn't stay eatable for a long time. therefore the meat is often packaged in plastic which cannot be recycled and ends up in the landfill. In addition, you need much area to produce it: both for the plants the animals eat, and for the animals.