Final answer:
The proper way to place bags into overhead bins is to gently slide them into the designated spaces to avoid damaging the bags or other items.
Step-by-step explanation:
When placing bags into the overhead bins on an airplane, the correct method is A) Gently slide them into the designated spaces. This ensures that your belongings and those of other passengers are treated with care and the overhead compartment can close properly. Option B is incorrect because it can damage the bag or other items in the bin. Option C may be done if you require assistance, but it's typically the responsibility of the passenger to store their own bags. Option D is another viable option, especially for smaller bags that may not fit in the overhead bins, but it does not directly answer the question about placing bags in overhead bins.