The teeth of some mammals show growth rings that result from the const

Another C.

(A) in an unusually early winter (then the previous layer would be thinner too)

(B) at roughly the same age (the number of layers might have varied among pigs; argument doesn’t say otherwise)

(C) roughly in midwinter (good – the last layer was only half the normal width)

(D) in a natural catastrophe (could be, but still, we can conclude only about the time when the death came, not about the cause)

(E) from starvation (the same - we can conclude only about the time when the death came, not about the cause)

(C)
The last band on all the pigs’ teeth was translucent. That means these last bands were deposited in the winter. But these bands are only half the normal width; since the depositing of cementum is supposed to be “constant,” this means that the bands were deposited in only half the normal time. In other words, the pigs stopped depositing
cementum about half-way through the winter. According to what we’ve been told, we would expect a pig to continue depositing cementum at a constant rate as long as it’s alive, so we can reasonably infer (C), that the pigs died about half-way through the winter.


(A) conflicts with the evidence. If the pigs had died in an unusually early winter, then the previous summer would have to have been unusually short. If the previous summer had been unusually short, then the opaque band deposited at that time would have to have been unusually narrow. Since all the bands other than the last were of constant width, the
previous summer was not unusually short. In turn, this implies that the fatal winter was not unusually early.

(B) We just don’t know the ages of the pigs at the time of their death; we could only calculate their ages if we’d been told the total number of rings in their teeth. As it is, we have no idea.

(D) misinterprets the evidence to suggest that all the pigs died at the exact same time, rather than that they all died at about the same time of year. In other words, (D) seems to suggest that all the pigs bought the farm mid-way through the same winter, but this need not be the case.

(E) goes beyond the evidence. Starvation is one of the things that could have killed the pigs in the winter, but we don’t know that it did; maybe they froze to death or they’re more vulnerable to predators in the snow.

Teeths of mammals show growth rings - opaque deposits in summer, translucent in winters.
Cross section of some ancient animal shows both rings of consistent width. Last width is translucent of roughly half the length.

(A) in an unusually early winter -- "roughly half" is not supported by "an unusually early winter". Eliminate.

(B) at roughly the same age -- Not supported by the argument.

(C) roughly in midwinter -- Correct choice. Paraphrasing the conclusion, the animals had died midwinters, resulting in half translucent ring as the last.

(D) in a natural catastrophe -- Not supported by the argument. Eliminate.

(E) from starvation -- Not supported by the argument. Eliminate.

The passage simply says that layer is deposited seasonwise i.e. opaque in summer and translucent in winter then again opaque followed by translucent and so on. So, how come the last layer is found to be half the width of the other layer that were of equal width. the last one being translucent means animals died in winter and since the width is about half the normal width, they must have died mid winter(with an assumption that layer deposition happen at constant rate).

A is 2nd best contender but loses out to C.

Answer C.