This is a really tricky question to be honest. I believe the answer will be 'has grown' as:
Among the given options it won't be 'have grown' as have is used for plural subjects (except for 'you' and 'I'). Here, the subject will be the 'seed of revolution' which is in singular form.
Now, there's 'has been grown'. This could be right but remember that the term 'seed of revolution' doesn't refer to the normal plant seeds but it signifies how people came to have the seed embeded within themselves and the intelligence to fight for their rights, thus starting a revolution. No one artificially grew this seed for it to 'have been' grown; it just grew naturally in the minds of the civillians.
Hence, 'has grown' seems to be the most apt answer.
Please do let me know if this is wrong or right. Thanks!
