Adding your Instagram profile link to your email signature and to your website:
A) has limited effectiveness because viewers need to have the Instagram app installed on their device to click through.
B) helps make it easy for people to find you on social media
C) is strongly recommended, but does require a minor amount of back end programming OR or a paid third-party widget like Iconosquare
D) is the only feasible ways to promote your Instagram account outside of actually engaging and content sharing on the platform.