Answer:
A. publicity
Step-by-step explanation:
Publicity is a promotional element which involves creating awareness of a product or service as well as making the product or service visible to the public. Publicity could be done through word of mouth, and most effectively, through the media. Publicity aims at exposing the public to new products or services, as well as creating public awareness as a form of promotion.
Since the discovery of the agrichemical laboratory is new, and also are constrained by very small marketing budget, the promotional element that the agrochemical laboratory can use in communicating its discovery is publicity.