In iTunes 188.8.131.52 the sync options is little bit confusing. I tried hard to find out this option. The otpion name shown in the iTunes 12 is confusing. The option check box shows “Automatically install new apps”. Here is the steps to sync the apps with iTunes 12.
Step 1. Click on your device as metioned in the figure
Step 2. Click on the Apps menu in the left side menu
Step 3. Check the Automatically install new apps box
Step 4. Click on Sync the iPhone and iTunes