What american scientist envisioned humans traveling to mars?

Wernher von Braun

Explanation:

Wernher von Braun was a German scientist and physicist who in his non fiction book " The Mars project" mentioned about expedition to mars by man. This book outlined technical specification for a manned expedition to mars in 1948.

He envisioned  a large space expedition where 70 crew members on 10 space crafts shall spend 443 days on the surface of mars. He even calculated the size and weight of ships and the required fuel.

c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.