Final answer:
Lamarck used acquired traits in his mechanism of evolution by proposing that acquired traits are inherited by offspring, as represented by option a) in the given choices. However, this theory has been largely discredited and is not supported by modern scientific evidence.
Step-by-step explanation:
Lamarck used acquired traits in his mechanism of evolution by proposing that acquired traits are inherited by offspring. This is represented by option a) in the given choices. Lamarck theorized that changes in an individual caused by its environment or the use or misuse of a structure during its lifetime could be passed on to its offspring, thus bringing about change in a species.
However, it is important to note that Lamarck's theory of acquired traits being inherited has been largely discredited and is not supported by modern scientific evidence.