What option is true about bait colors used by manufacturers?

Manufacturers often color grain baits specifically to deter birds, which makes this option true. The use of color in bait design serves dual purposes: it can enhance the effectiveness of the bait for the targeted pests while also preventing use by non-target species such as birds that may otherwise be attracted to the bait. This consideration is crucial in agricultural practices where protecting beneficial wildlife and minimizing non-target interactions is a priority.

The other options do not accurately reflect the nuances of bait design. For instance, while some dark colors may be appealing to specific pests, it is not universally true that dark colors are always more attractive. The efficacy of colored baits can vary based on the species they are designed for; thus, not all colored baits are equally effective, and the significance of bait color cannot be dismissed entirely, as it plays a role in pest attraction and control strategies.