Final answer:
The correct verb form to complete the sentence is 'pierda'.
Step-by-step explanation:
The correct verb form that completes the sentence is pierda.
This is because the sentence is using the subjunctive mood to express importance. When we have an impersonal expression like "es importante que" followed by a verb, we use the subjunctive form of the verb.
For example, in the sentence "Es importante que no se pierda la batalla para salvar el medio ambiente," the verb "pierda" is in the subjunctive form to convey importance and uncertainty.
Learn more about The correct verb form in Spanish