Why velocity is regarded as a vector quantity?​

Because velocity has magnitude and direction, speed is not a vector quantity since it only has magnitude

For example, if a car is moving backwards with a speed of 40m/s

Your velocity is - 40m/s

Speed is 40m/s

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.