Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

[Q]: Passage: The plugs-out test began on the morning of January 27, 1967, and immediately was plagued with problems. First the crew noticed a strange odor in their spacesuits, which delayed the sealing of the hatch. Then, communications problems frustrated the astronauts and forced a hold in the simulated countdown. During this hold, an electrical fire began in the cabin, and spread quickly in the high pressure, 100% oxygen atmosphere. Pressure rose high enough from the fire that the cabin burst and the fire erupted onto the pad area, frustrating attempts to rescue the crew. The astronauts were asphyxiated before the hatch could be opened. Question: What was the first problem astronauts encountered during the plugs-out test?
[A]: strange odor in their spacesuits


[Q]: Passage: The concept of prime number is so important that it has been generalized in different ways in various branches of mathematics. Generally, 'prime' indicates minimality or indecomposability, in an appropriate sense. For example, the prime field is the smallest subfield of a field F containing both 0 and 1. It is either Q or the finite field with p elements, whence the name. Often a second, additional meaning is intended by using the word prime, namely that any object can be, essentially uniquely, decomposed into its prime components. For example, in knot theory, a prime knot is a knot that is indecomposable in the sense that it cannot be written as the knot sum of two nontrivial knots. Any knot can be uniquely expressed as a connected sum of prime knots. Prime models and prime 3-manifolds are other examples of this type. Question: For a field F containing 0 and 1, what would be the prime field?
[A]: the smallest subfield


[Q]: Passage: Despite their soft, gelatinous bodies, fossils thought to represent ctenophores, apparently with no tentacles but many more comb-rows than modern forms, have been found in lagerstätten as far back as the early Cambrian, about 515 million years ago. The position of the ctenophores in the evolutionary family tree of animals has long been debated, and the majority view at present, based on molecular phylogenetics, is that cnidarians and bilaterians are more closely related to each other than either is to ctenophores. A recent molecular phylogenetics analysis concluded that the common ancestor of all modern ctenophores was cydippid-like, and that all the modern groups appeared relatively recently, probably after the Cretaceous–Paleogene extinction event 66 million years ago. Evidence accumulating since the 1980s indicates that the 'cydippids' are not monophyletic, in other words do not include all and only the descendants of a single common ancestor, because all the other traditional ctenophore groups are descendants of various cydippids. Question: When did the Cretaceous-Paleogene extinction happen?
[A]:
66 million years ago