a) They (social class dialects) are grammatical differences between the speech of two or more speakers which gives us clues as to their social background.
b) As well as having an accent such as a person from Latin America trying to speak English; but there are also "social class" accents.
c) Languages reflect the internal differences between various human societies.
d) Different social groups use different linguistic varieties.
e) We as individuals have also learned to classify socially acoordingly just by listening to their pronounciation and grammer.
f) Dialectologists have found that regional-dialect boundries often coincide with geographical barriers such as mountains, rivers, swamps etc.