IMHO, A is wrong because of how strong it is. What makes it strong is the usage of “will have to”. The literal meaning of A basically says that unless we solve this problem, employees do not have any other choice but to encrypt the texts. If it used something like “might have to” there would be more potential for this to be the correct answer. Author also hinted that it is inconvenient practice at the end of the passage, which can be further inferred that not everyone will practice encrypting their messages. Avoid strong terms on conclusion/main point questions unless there is same strength present in the passage (happens pretty rarely).

You got this!!!!