What are the answer choices? If you have climax then thats your answer (:
        
                    
             
        
        
        
Here we can observe that the verb used doesn't reflect the correct tense to express when this action took/is taking/will take place. There are many tenses where you could choose from, depending of the time of action:
Tenses: Simple, Progressive, Perfect, Perfect progressive
Times: Past, Present, and Future
Imagine all the combinations!
The simplest example we could make is if this action is a routine that happens continuously, the action verb (invite) is changed to simple present for the third person of singular (invites): 
<span>Tommy, in an effort to maintain clowning's positive roots, invites dancers to weekly performance battles.</span>
        
             
        
        
        
To combine these sentences together to flow neatly and be grammatically correct you could say: Early airships such as zeppelins were filled with hydrogen, but today's blimps use helium instead. This is the correct answer out of your choices.
Your answer is: Early airships such as zeppelins were filled with hydrogen, but today's blimps use helium instead. 
Have an amazing day and stay hopeful!
        
                    
             
        
        
        
Answer:
<em>Senator G.A Nelson originally created Earth Day in order to help issues with mass pollution. This helped bring a wake up call to large industries and lazy politicians.
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</em>Explanation:
<em>Hope this helps</em>
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