Option A represents correct punctuation for the given sentence since there is a full stop after first independent sentence.
The en dash (–) is used to mark ranges and with the meaning “to” in phrases like “Dover–Calais crossing.” However, it should not have been used to join two independent clauses.
Colon is used if there is a need of coordinating conjuction. Hoewever, in this sentence there is no need of a coordinating conjuction.
Comma is used if there is a need of coordinating conjuction. Hoewever, in this sentence there is no need of a coordinating conjuction.
Option A represents correct punctuation for the given sentence since there is a full stop after first independent sentence.