The sentences below have words that are missing. Choose the best option from those given below to complete the sentence.

Everyday more than 1 billion promotional messages are sent that are commercial and __________. Although __________ have used more technology to stop this, _______ find ways around it.

We can fill in the given triplets in the sentence and interpret them to find the one that best conveys the meaning:

• A. Everyday more than 1 billion promotional messages are sent that are commercial and educational. Although firewall have used more technology to stop this, hackers find ways around it.
• B. Everyday more than 1 billion promotional messages are sent that are commercial and inescapable. Although governments have used more technology to stop this, advertisers find ways around it.
• C. Everyday more than 1 billion promotional messages are sent that are commercial and informative. Although authorities have used more technology to stop this, promoters find ways around it.
• D. Everyday more than 1 billion promotional messages are sent that are commercial and unsolicited. Although regulators have used more technology to stop this, spammers find ways around it.

Out of the given four choices, option D fits the context best. 'Unsolicited' messages are messages that have not been subscribed to. 'Regulators' would employ methods to safeguard people from unsolicited messages sent by 'spammers.'