Could not find android.jar for API Level in xamarine andriod

Severity Code Description Project File Line Suppression State
Error Could not find android.jar for API Level . This means the Android SDK platform for API Level is not installed. Either install it in the Android SDK Manager (Tools > Open Android SDK Manager...), or change your Xamarin.Android project to target an API version that is installed. (C:\Program Files (x86)\Android\android-sdk\platforms\android-\android.jar missing.) OSDAMobileApp