Read the list of sentences from the article.

1. carbon dioxide concentrations have skyrocketed far higher than any levels in more than 800,000 years, according to data from the scripps institution of oceanography at the university of california, san diego.

2. "not just in recorded history, not just since the invention of agriculture 10,000 years ago. since before modern humans existed millions of years ago."

3. carbon dioxide levels millions of years ago were higher than 2019 levels, but earth's temperatures were also far higher.

4. in the 800,000 years before the industrial revolution, co2 levels didn't surpass 300 parts per million.

which two sentences taken together provide the best evidence to support the idea that the co2 levels we are experiencing now are abnormal?

a
1 and 3
b
1 and 4
c
2 and 3
d
2 and 4

Comedians like to joke that the reason we haven’t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earth’s broadcasts of intellectually embarrassing tv programs, like gilligan’s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. let’s check the assertion that aliens could have been receiving them. tv programs are broadcast at a frequency of about 100mhz with about 100kw of total power in 30frames per second, which emanatesroughly uniformly in all directions. assume that interstellar space transmits these broadcasts without attenuation. no matter how smart they are, aliens would require at least one photon per frame to interpret our signals. findthe number of photons per unit time per unit area reaching a receiver on a possible planet in the nearest star system, which is about 4 light-years away (a light-year is the distance light travels in a year). if aliens aimed a receiver or detector directly at earth, how big (in diameter) would it have to be to receive a photon per frame

An electron is traveling with initial kinetic energy k in a uniform electric field. the electron comes to rest momentarily after traveling a distance d. (a) what is the magnitude of the electric field

The center of the milky way most likely contains a. empty space. b. a red giant star. c. a globular cluster. d. a supermassive black hole.