Correct option is A
The correct answer is (a).
According to the International Code of Botanical Nomenclature (ICBN) rules, an isotype is preferred over a syntype in the case of lectotype designation. Isotypes are copies of the type specimen that are preserved in different locations, and they are considered to have equal status to the original type. Syntypes, on the other hand, are multiple specimens designated when no holotype was originally chosen. The preference is to choose an isotype over a syntype because isotypes are considered a more reliable representation of the original type.
Incorrect options-
Option (b) is correct because an isotype is always preferred over a syntype due to its direct association with the holotype.
Option (c) is correct because when syntypes or isosyntypes and isotypes are unavailable, paratypes may be selected.
Option (d) is correct as a last resort, when no type material is available, a lectotype may be selected from original uncited specimens to stabilize the name.
