Two true sentences about Article 19 are placed side by side here, but they are doing opposite jobs. One celebrates the freedom, the other fences it in. Spotting that mismatch settles the question.
Why the assertion is true: democracy runs on informed choice. Citizens need to hear criticism, read reporting, and argue in public before they vote. Strip the speech away and elections become theatre. That is why free speech is treated as the liberty on which the others depend.
Why the reason is true: the Indian Constitution never made this freedom absolute. Article 19(2) permits reasonable restrictions on eight grounds, and public order is one of them, inserted by the Constitution (First Amendment) Act, 1951 after early Supreme Court decisions had read the original clause narrowly.
Why the link fails: notice the subject matter. The assertion answers "how important is this freedom?" The reason answers "how far can this freedom be curtailed?" The second question does not supply an answer to the first. If the reason explained anything, it would explain that the right has boundaries, which is close to the opposite of what the assertion claims.
Let's summarize:
So both are true, the reason is not the explanation, and option (B) is the answer.