Why are PDF fi les a universally popular format for distributing reports electronically?

Why are PDF fi les a universally popular format for distributing reports electronically?

a. Senders appreciate the ability to maintain control over how their documents appear on the receiving end.
b. Receivers are oft en reluctant to open word-processor fi les.
c. Most businesspeople expect most reports to be distributed as PDF fi les.
d. All of the above are true.