During the Silurian,the Oxygen Gas Concentration in the Atmosphere Is

question 7

Multiple Choice

During the Silurian,the oxygen gas concentration in the atmosphere is postulated to have reached an amount equivalent to more than 10 percent of its present-day concentration.Thus,nearly all lethal ultraviolet radiation was unable to reach the Earth's surface,making dry land available for newly evolved forms.Which of the following major events in the evolution of animals and plants probably occurred at this time?

• A)The amphibians developed watertight skins and eggs.
• B)The crayfish become the first land organisms.
• C)The first major groups of seed plants appeared.
• D)Primitive bryophytes and fern-like plants appeared.

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Definitions:

2 × 4 ANOVA

A type of Analysis of Variance test that examines the effect of two independent variables, each with two and four levels respectively, on a dependent variable.

Gender

Social and cultural distinctions associated with being male, female, or non-binary, rather than biological differences.

Region of Residence

A demographic variable denoting the geographical area in which an individual lives.

Analysis of Variance

A collection of statistical models and their associated procedures which compare means by partitioning variance into components attributable to various sources of variability.