Blood pressure of human body is measured only at the site of arm only, why

the heart supplies the organs and tissues of the body with blood with every beat  it pumps blood into the large blood vessels of the circulatory system the   Blood pressure readings are made up of two values:

systolic blood pressure is the pressure when the heart beats while the heart muscle is contracting and pumping oxygen rich blood into the blood vessels

diastolic blood pressure is the pressure on the blood vessels when the heart muscle relaxes the diastolic pressure is always lower than the systolic pressure

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.