您正在制作应用广告系列，现在需要考虑广告素材资源。 对于一个应用广告系列中的每个广告组而言，HTML、图片和视频素材资源的数量上限是多少？

The correct answer is 20. For each ad group in an App campaign, you can upload up to 20 HTML5, image, and video assets. This allows for extensive testing and optimization of different creative elements to find what resonates best with your target audience. Options like 5, 8, or 10 are incorrect because they are below the actual limit, restricting your creative options. While 20 is the maximum for each asset type, it's important to note that Google Ads recommends providing a diverse range of assets to maximize campaign performance.