Consider the scenario below and answer the question that follows:

ThreadOn chose to have a launch event on $27$ February $2022$ for its new sustainability product range, namely the Gauran$-$TEE range. At the lavish launch, ThreadOn treated its various stakeholders to impressive food and entertainment. The event drew many reporters who broadly featured the new range in favourable light on their respective social and media channels.

$\_\_\_\_\_\_\_\_$ was the main technique used by ThreadOn to communicate the message about its new sustainability range.

Select one:

a$.$

Public$-$relations

b$.$

Sponsorship

c$.$

Sales promotion

d$.$

Social marketing