To agree with many others, I think the product is overall the most essential part of the four P's. You can have the best promotion, price, and placement, but at the end of the day it's the product that goes home with people or gets used and if it doesn't meet their need or isn't reliable, it's hard to maintain success. Reviews are a big part of business now a days and despite how you sell your product, if it doesn't hold up or accomplish what it needs to, it may take on a bad reputation. A solid product will set the tone for the rest of the marketing mix, once you know what makes the product valuable, then you can follow with how to price it, where to place it, and how to promote it. All the other P's stem from the product. I would say the most difficult is promotion. With the amount of content that is consumed now a days, it is hard to create something that actually grabs the attention of the consumer enough to not be anticipating when they skip the ad or scroll away. And not only does it have to grab their attention, but it has to appeal to them and reach the targeted audience. With social media, companies have to stay up to date with trends and constantly find new and creative ways to connect with their audience without feeling repetitive or forced. It is definitely a challenge to stay relevant while keeping your brand's message and goal consistent.