This weakens the argument, because it proposes an alternative explanation for the differences between the scavenging and non-scavenging baboons. If we can’t accurately compare the impact of garbage between these groups, the argument is weakened.

Like (C) and (E), this weakens the argument by adding a new way that eating garbage could harm the baboons’ health. If the scavenging baboons grow faster and have more offspring, but also die faster, it becomes much harder to say that garbage does not harm them.

Like (B) and (E), this weakens the argument by giving us another example of how garbage could be harming the baboons. This rebuts the author’s assumption that growth speed and birth rates are the only relevant markers of the baboons’ health, thus weakening.

This does not weaken the argument. If these garbage dumps are helping the hyena population grow, that may even strengthen by demonstrating another species that isn’t harmed. Even if not, this doesn’t give us any reason to doubt the argument, so does not weaken.

Like (B) and (C), this weakens the argument by demonstrating a harm possibly caused by the garbage dumps that the author has overlooked. This harm isn’t just to the scavenging baboons, but the timing relative to the dumps opening suggests a possible causal link, thus weakening.