revised part 4 of the module

Author: threeal

Assets/Prefabs/Background.prefab

@@ -14,7 +14,7 @@ GameObject:
   - component: {fileID: 5799543162257971287}
   - component: {fileID: 5799543162257971280}
   - component: {fileID: 5799543162257971281}
-  - component: {fileID: 5799543162257971282}
+  - component: {fileID: 2584630358113178937}
   m_Layer: 0
   m_Name: Background
   m_TagString: Untagged
@@ -190,24 +190,15 @@ BoxCollider2D:
   serializedVersion: 2
   m_Size: {x: 17.777779, y: 1}
   m_EdgeRadius: 0
---- !u!50 &5799543162257971282
-Rigidbody2D:
-  serializedVersion: 4
+--- !u!114 &2584630358113178937
+MonoBehaviour:
   m_ObjectHideFlags: 0
   m_CorrespondingSourceObject: {fileID: 0}
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 5799543162257971283}
-  m_BodyType: 2
-  m_Simulated: 1
-  m_UseFullKinematicContacts: 0
-  m_UseAutoMass: 0
-  m_Mass: 1
-  m_LinearDrag: 0
-  m_AngularDrag: 0.05
-  m_GravityScale: 0
-  m_Material: {fileID: 0}
-  m_Interpolate: 0
-  m_SleepingMode: 1
-  m_CollisionDetection: 0
-  m_Constraints: 4
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 2c6e672b72661a54da1dc239df97dfd1, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: