Squirrels’ preferences for other foods are irrelevant to the argument. Lydia and Galina are discussing squirrels’ motivations for consuming tree sap––we know that the squirrels consume the sap; Galina and Lydia just disagree about if they’re eating the sap to get the sugar.

The topic of the argument is squirrels’ motivation for consuming sap. (B) just provides information about squirrels’ behavior patterns, but it does not say anything that could help determine whether squirrels are consuming the sap in order to get sugar, or for some other reason.

Information about sugar concentrations in other trees is irrelevant. The arguments discuss squirrels’ motivation for consuming sugar maple tree sap; we don’t care about other trees. We don’t know why the squirrels are avoiding the other trees, and it’s the “why” that counts here.

This weakens Galina’s argument because it shows that the squirrels are able to access the sugar in the sugar maple tree sap without drinking an enormous amount of sap. (D) makes it so that Galina’s premise does not provide support for her conclusion.

The arguments discuss squirrels’ reasons for consuming the sap. (E) tells us that accessing the sap may be difficult, but does not address squirrels’ motivations, so it does not weaken the argument.